Metric Vs Imperial

by | May 10, 2013 | 70 comments

Since learning metric measurements in school I’ve always been a user of the millimetre and never questioned its suitability. Richard was also taught metric first but as soon as he was out in to the practical world of work he adopted the use of imperial finding it much more intuitive. If he hadn’t put up an argument every time I presented a drawing in mm I think I would always have called the inch outdated and inferior. It just makes so much more sense to me to divide a measurement in to 10 equal parts; so much more simple to turn it in to a decimal or fraction. But sometimes we have to realise that our loyalty is simply a stubbornness through desire to stick with the familiar and since Richard can be so very persuasive I started to understand where he was coming from.

Despite the UK’s move to the metric system many moons ago it seems that there are great numbers still clinging on to their feet and inches so there has to be something that gives it an edge. Richard has often told me that it’s the centimetre that’s the problem and he’s not the only person I know who finds it a bit puzzling looking at cm’s when taking large measurements. After several years of becoming more familiar with imperial I think I’ve sussed why the cm is deemed by some as the measurement from Hell! It’s about the ratio between the various units in the system.

A centimetre of course is ten times larger than a millimetre and a metre is one hundred times larger than a centimetre. That’s a perfect relationship for simple mathematics but it isn’t very well balanced when visualising it on a tape measure. A centimetre divides up nicely in to small and accurate millimetres but compare a centimetre to a metre and it’s so small it gets lost. To aid this problem we tend to find that tape measures use a visual queue (a bold line or red number) at every ten centimetre interval and some goes as far as to miss any extra emphasis when we come to a metre instead continuing by calling them 100, 200, etc.
Dividing a metre in to ten like this is much more helpful when measuring long distances than seeing hundreds and hundreds of centimetres but this unit doesn’t really exist with its own name. The red ’20’ on the metric side of the tape in the photo is the location of 120cm but looking at it in isolation this isn’t immediately clear and to add to the confusion the same numbers ‘1- 9’ run continuously along the tape.

By contrast imperial units come without the ease of having to only understand your ten times table. A foot is made up of 12 inches and an inch becomes progressively smaller in divisions of 8, 16, 32 & even 64 should you need to go that small. This makes life difficult at the drawing board but just look at the photo to see how much clearer it makes things in the real world of full scale measurements. Long distances can be read simply with the bold and continuous markings of both inch and feet and if accuracy is required every 1/16″ is also noted. Finding 49″ inches or 4′ 1″ on that tape certainly jumps out much clearer and quicker than searching for 1.24m,  124cm or 1240mm.

The relationship between an inch and foot makes heaps more sense than that of a centimetre and metre and yet I would still never give up my metric system when making scale drawings. Perhaps then we will always continue to keep both versions alive as each definitely brings its own strengths for particular applications. It’s a prime example of when one thing is more suited to theory and another to practise. So…what do you use, and why?


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Helen seeks to explore ways to live with greater joy & sustainability for both ourselves & the planet. Concepts which have led to the launch of her second business We Are Carbon. As the producer of our videos, Helen brings a unique perspective & injects life to our education ensuring it is both a pleasure to watch & easy to follow & learn from. Learn More About Helen & The English Woodworker.


  1. Paul Chapman

    I was taught imperial measure at school so I tend to visualise everything in imperial. I’ve found that if I try to make things using metric measurements I usually get into a mess, so I stick with imperial – and I’m too old to change now! The only exceptions to this are metric nuts and bolts because you can do everything with about three spanners rather than having to have a box full. And when driving abroad, kilometres are shorter than miles so you seem to get everywhere quicker!!

    • Helen

      Thanks Paul, the nuts and bolts are a good one to bring up, I’d be very lost trying to work with anything other than metric for those!

    • bill

      inches don’t divide into thirds

      • Ivan Walker

        Do centimetres divide into thirds?

        • Joseph

          Touché! 🙂

    • Brian Johnston

      Like you I was brought up with the imperial system (I was born in 1948) and used it right through to starting work as a quantity surveyor (construction accountant in the USA) at age 16. A couple of tears later the building industry started to go metric, with the result that I am perfectly at home in metric or imperial. So much so that I still tend to think in feet and inches as my general measurement system but tend to use millimetres for small measurements. Its much easier to count millimetres and eyeball the fractions thereof, refined to “full or bare”, than to try to work out if that’s 17 or 19/64ths of an inch.

      Incidentally, the construction industry has never used the centimetre: only metres and millimetres.

  2. Chris Buckingham

    You are spot on in your theory about the relative size of Metric verses Imperial units,I think the Metric system,useing as it does units of ten,appears to be a gift from heaven when a teacher is trying to get measurement accross to students,however,when faced with trying to pick up a piece of wood that is 24″,or 2 Foot long,it in my opinion,much easier than trying to estimate 61 Cm,or even 610 mm.
    Living in France,as I now do,I find that even here there is a certain amount of confusion over what units to use,some never use mm,and use the Cm, and some only use mm,which can be a pain as the mm is such a small dimension (.0395″) that one can hardly imagine more than very few of them as a dimesion,the Metre is not as bad as it is almost the same as our Yard,so we can take them to be the same if we are estimating something the size of a field.
    Being an engineer I normally measure in thousandths of an inch anyway,but there are other units used such a Standard Wire Gauge,and of course the British Standard Pipe Thread,which is used all over Europe. So we mix and match according to our needs. The excellent gentlemen like Joseph Whitworth who devised such marvelous British Standards to adhere too must be spinning in thier graves!

    • Helen

      Hi Chris, it’s very interesting that you should mention about confusion even between using the cm and mm – units from the same system. Inches and feet seem to work much more hand in hand where as we wouldn’t say 12cm 7mm, we’d choose between one or the other.

      • Vlad

        12 cm and 7mm is 127 mm or 12.7 cm. I’m drunk and trying to learn imperial, however, when I saw your post, drunk as I was, it instantly came into mind that 12 cm and 7 mm is 127 mm. I guess it’s just a matter of habbit. Btw, I know this post is almost 24 moons away, which is 4320 beers ago, however, I felt the need to comment it.

    • kiwi-ian

      Why would you need a piece of wood exactly 2′ long?

      Measures are like languages, if you keep translating you get a stilted dialogue, but if you think in that language, it flows.

      I think in metric. so I would pick up a 60cm piece of timber. In real, human terms it is very little different from 2′. I use 500g jam jars, 1 lit milk cartons and 1 kg sugar bags, I am 1.9m tall, the man next to me weighs 120kg, I know how fast 50 kph is because it’s the urban speed limit here. My car has a 1.6 lit engine (small) while my wife’s is 3.5 lit.

      For those that work every day in the metric system, there are “human” level measurements, they just aren’t the same as for imperial. We can easily visualise 30cm instead of a foot, we can visualise a 10m high tree or a 5km walk. They are different but still just as valid.

      One of the inherent characters of a “human” level system is that it contains errors. When you say a tree is 30 feet tall, you are only approximating. In fact the error is often so large that a 10m tree is just as good!!

      Once you have acquired these metric human measures – and they are not difficult, the ease of calculation and the inter-relationship between units just makes metric vastly superior.

  3. Dave

    Helen, I use inches and feet, as I have grown up using that system. However your essay is one of the best I have read explaining the difference and why the seperate systems are used

    • Helen

      Thanks Dave, I think most of us like to stick with what we’ve grown up with. I’ve started to use inches much more these days to work alongside Richard but for smaller measurements I think I’ll always think in mm.

  4. MStone

    Base 12 and base 16 divide into more equal parts then base 10, metric only divides by 2 and 5. This means it is MUCH easier to think proportionally using imperial. Halves, quarters, eighths, thirds (in the case of inches) and sixteenths, easy in imperial, next to impossible in metric. I work in professional theater, I’ve seen dozens of designers from overseas, (metric using countries) that can’t see proportionally. Their designs tend to look like your looking at them through a warped lens.
    You can work proportionally in metric, you just end up with some weird numbers, which as mentioned in this article, can be hard to locate on your layout tools, and aren’t standard sizes of materials or hardware.

    I took a lot of physics in college, loved metric for that.

  5. Jeremy

    As a US resident, it seems stacked against me to go metric, which appeals to my engineering sensibilities (The company I work for uses mm to make very big things) I longed to use metric, until I realized it’s more challenging (in practice) to divide spaces. Metric works extremely well for dividing by 2,5,10. Whereas imperial works ok for 2,3,4,6,12 (possibly 8&16 too) divisions, but these are more the artistic divisions for design in. I don’t mean to imply either system is limiting (especially when using fewer actual measurements) but I think your point of theory vs practice is a good one. It’d be an interesting area for research (for a George Walker/Jim Tolpin type) as to whether this simplicity of unit division has any impact on cultural design bias.

  6. Paul Rodgers

    Seems I have something in common with Chris. As an engineer I was brought up on imperial (and log tables) and often have to use a calculator to do a quick conversion from the new metric sizes quoted in all technical data. I know what a five thousanths of an inch feeler gauge feels like and find the 40 threads per inch of a micrometer second nature. I too live sometimes in France and have had to get used to 14 and 16mm pipe and all the various pipe fitting threads and the times I have had to return to the Brico (French B&Q)is nobodies business. You can imagine my joy when I came across 1/2 BSP. My wife thinks I’m loosing it and, if I’m honest, I have to agree with her. On my next trip I’m going to attemp to introduce myself at the local timber merchant….a length of 3×2 s’il vous plait

  7. mihai

    I’d put the question somehow different : it’s not what we use , but what are -we doing with it; I was taught in metrics , – and for the last -say- 40 years that was not a problem , even when I had to design 20 mils traces of thin copper on my printed circuit boards. One mil is(was) 1 inch per 1000 and it was okay. The Idea is that even the US guys reached that point where ‘one thou’ was more practical than 1:1024 -got by successive halving…
    Imperial is older more practical , metric -younger , more intuitive , but , hey , what about one year-light ?
    There are two cultures , the price of communication (in this case , a simple conversion) , and people willing to pay -it….

    A day -before yesterday , I read something extraordinary on the web : “there are 10 kinds of people : people who understand binary and people who don’t”

    ‘Love you , guys.

  8. mihai

    Sorry , I forgot something []

  9. Chris Wong


    As a Canadian in my twenties, I learned the metric system in elementary school. However, I’m not sure how much I used it in the real world. I weigh myself in pounds and measure my height in feet and inches. The distance I travel is in kilometers and metres. When I began working with wood, I continued to use feet and inches, as that is what almost everything is measured. I have become reacquainted with millimetres recently since Festools invaded my shop.

    Recently, I taught a woodworking seminar and each of the six students were given a steel rule with Imperial graduations. Five were fractional and one was in decimal inches. Interestingly, a few students commented that they found the decimal rule easier to use and insisted on using it.


  10. Damien

    I use continuous metric tape measures, with a smaller font, what I lose is the ability to read them from the other side of the room.

  11. Chris

    Hi there,

    Just wanted to say, that when I was taught technical drawing using the metric system at school, they highlighted the problem here, and it all boils down to teaching. We normally quote metric incorrectly, the cm is not actually a unit of the metric system purely something invented to make teaching easier. The correct units in the metric system are millimeters, decimeters (100mm) and meters (1000mm). That’s why a metric tape highlights the 100mm or 10cm marks, in practice I find it easier to work in millimeters and meters, for any new project. However the problem arises when you work on anything built prior to decimalization where by you have to work in imperial to match sizes accurately. I think the only real answer is for the modern British woodworker to be versed in using both systems. That’s how I work anyway, and it works for me.

    • Andrew

      Chris, centimeters are undebatably a unit in the metric system. Your comment about decimeters is important though – it helps a lot to have a unit that keeps its count in a reasonable range. In Czech Republic for example, meats and cheeses are typically ordered at the shops in decigrams! So the unfortunate fact is that in many cases units which would make understanding measurements easier, like decimeter and decameter, are sadly left unused.

      The imperial system does seem have a leg up when it comes to proportions, a quarter of a foot is a lot easier to figure out than a quarter of 30 centimeters.

      • Andrew

        I second the comments about decimeters, which the main article implies doesn’t exist. I have a Dutch and Hungarian background and both countries use the deci. And similar to the mentioned Czech, my Hungarian mother cooked by decigrammes and decilitres.

        I see decimetres not as 100mm, as Chris mentioned, but as one tenth of a metre (10 dm to 1 m) and a dm is equal to 10cm. Deci after all means 10 (e.g., decade).

  12. Brian Eve

    Hi Helen,

    Another thing one might think about is whether or not your tools are in metric or imperial.

    I think it is important to pick one or the other when starting your tool hoard.

    In other words, if you plow a groove with a 3/8″ blade, don’t try making a matching mortise with an 8mm chisel.

  13. sylvain

    If you have always used metric, there is no difficulty to know what 61 cm is. On the other hand I have no idea what 34″ might be; I have to multiply it by 2.5 to have a rough idea (by 2.54 to be precise). I wander how an imperial guy sees 34″? Is it 2ft + 10″ or is it 3ft – 2″? What mental picture do you have?
    The m is the basic unit. The centimeter is not less legitimate then the decimeter or the mm. Of course in engineering you prefer to use multiples of 1000.
    I don’t see any advantage of using dimensions like 2X4 where in reality what you receive from the lumberyard is much smaller. Many dimensioning system used in USA are made with the point of view of the producer and not the one of the consumer. Example wire gauge system. I don’t care how many wires the producer could make starting from a given piece of copper. I just want to know what I receive for my money.

  14. Nikolaus

    Hi Helen, hi folks,

    very interestin discussion!
    Since I’m German, I naturely grew up with the metric system. I started reading English and American Blogs etc and so I had to deal with the Imperial system. And I agree with Helen, that its so much more intuitiv to use! But I can’t deal with 16th and smaller. So in woodworking I often find myself using inches and feet, but millimeters for small measurements. Works fine for me.
    And I agree with the comment, that the imperial system helps to the proportional thinking!

  15. JH

    being from Germany, I’ve always used the metric system. I agree that the tape measure in the picture above is confusing – my folding rule has its cm marks from 1 to 200.
    What does it matter how hard it is to imagine 61 cm? if it’s just for your working process, you use what you want, and if you want to buy lumber and have to use metric, you better have a tape measure or folding rule with you anyway. and if all else fails – I know that if I spread my hand completely, it’s 23 cm from the tip of my thumb to the tip of the pinky. or 9 inches.
    anyway… everyone should use what they like best, but dont blame it on your “§$%$% tape measure 🙂

  16. Jon V


    Being French I grew up using the metric system but I read a lot of material where the author uses the imperial system. In France the cm is a widely used unit in every day life, as are millimeters, for any measurements under 1cm and maybe up to 10cm and meters. A length over 1m will usually be refered to as 1m and Xcm. The dm is very rarely used. Basically I think it mostly comes down to what you are used to… I have no problems visualizing 61cm but anything over 6 inches and I have to start multiplying by 2.5.
    One area where the metric system might make life easier is when adding and subtracting as no fractions are involved.

  17. John

    Hi Helen,
    A very interesting article, highlighting not the problem with metric measures, but how they are used, and the use of instrumnets (ie measuring tapes) that are not metic friendly.
    Some friendly advice.
    1) Dont use hybrid tapes, as shown in your picture.. They are the bane of anyone measuring in metric, because the metric measure is always on the bottom edge, making measurements in metric awkward. When measuring in metric use a full millimetre tape.
    2) Dont use a metric tape that is hybrid, (ie that uses millimetre markings but centimetre numbers) as in your picture. I use a tape that is numbered 100, at the 100 mm mark, 200, at the 200 mm mark, etc, and 1000, at the 1000 mm (1 m) mark, 2000, at the 2000 mm (2 m) mark etc. Using your example, at the 1.2 m or 120 cm mark, my tape, because it is a full millimetre tape, has the number 1200, to label the 1200 mm mark. Its easier to use a full millimetre tape. I think it may be difficult to find full millimetre tapes in the UK but Stanley do make them (eg: Stanley part number 30-528 or 33-732)
    3) Always use millimetres, or metres for longer lengths. Only ever use the centimetre for body height or waist measurement when purchasing clothing. Using millimetres, rather than centimetres, removes any decimal fractions,and therefore reduces the likelyhood of errors.
    4) One disadvantage, not of metric measures, but of metric tapes, compared to Imperial tapes, is the length of the markings, which can help or hinder the indentification of the correct measurement mark. Notice, how in your picture, that the Imperial marking have different lengths, while most of the metric markings, have the same length. This makes the metric tape more difficult to read. This not the fault of metric measures, but of the tape manufacturers, who bias the tapes so makings on the Imperial tape are easier to read.

    I hope you find this comment helpful
    Thanks for the opportunity to comment.

    • Helen

      Hi John and thanks for a very thoughtful comment. I think there’s certainly a lot of compromise in using a tape that covers both metric and imperial because often there’s a bias towards one side or the other. I like to use a mixed tape most of the time but I find the example I’ve photographed here particularly terrible for when metric is required.
      Thanks again.

  18. Stephen Guest

    Hello, I’ve not posted before but I do enjoy reading the blog when I find the time. I worked at my father’s joinery initially and most of the people I learnt from had trained in imperial. I subsequently worked with different firms before ending up setting up on my own business. My main point is that when I measure up for a job, be it a window or door it’s most often in a Victorian or Georgian house so it’s easier to measure in Imperial as the original was made in those proportions. When I draw up the rod, and manufacture the item I am most comfortable working with MM. Also I actually like a ‘hybrid’ tape to measure-up and a folding wood MM rule at my bench. Surely it’s about what works best for you? I just try and take my time and cut to the line. Steve.

    • Helen

      Hi Steve, you make a very good point and of course it’s generally going to be the case that when out measuring up something existing and made by someone else it’ll be more straight forward to take measurements down in the system that it was designed and built in – definitely beneficially then to be at least somewhat familiar with both.

  19. Alvaro

    Hi, I’ve always used metric system but now when getting into woodworking I have learned to use the Imperial system as well.

    Just a thougt from a different angle, just for not being repetitive, is that I’ve improved my fraction arithmetic using the imperial system… I think is a great way to teach fractions to children


  20. Jim

    The divisibility of 12 is a major advantage of inches and feet. 10 is only divisible by 5 and 2, but 12 is divisible 2,3,4,6 (and sort of 8). This makes measuring 1/4, 1/3, 1/2, 2/3, 3/4 of a length much easier with feet & inches. Consider that there are 360 degrees in a circle for similar (but not quite the same) reasons. This is not accidental. Metric seems easier to us today in the age of digital calculators, but in the age of mechanical dividers and slide rules, 12 segments is superior. The imperial system is not arbitrary or random, as I had long suspected; it has a logic of its own.

    Great blog!


  21. Jim Linn

    Sorry everyone, I use millimetres alone. I’ve built everything from boxes to buildings in just millimetres. All my rules are metric. I rarely misread with this method. One unit for everything works for me. I also use kilos and litres at work. Except altitude, speed and distance which are in feet, knots and nautical miles. Funny that.

  22. Bill

    The Metric system was developed in 16th and 17th century BEFORE digital calculators. It was a system designed “for all people for all time” unlike the imperial system.

    Incidentally I use both systems interchangeably. Nothing wrong with being bilateral.

  23. Mark Roberts

    “Dividing a metre in to ten like this is much more helpful […] but this unit doesn’t really exist with its own name.”

    So… what’s a decimetre?

    The main advantage of imperial measurements is that 12 is easily divisible by 3. Unfortunately, someone had the not-so-brilliant idea to divide inches into 8ths / 16ths / 32nds (instead of 12ths), which completely wasted that advantage for small measurements.

  24. peter

    i have always used metric but never centimetres always millimetres a long board would 3 metres 660 millimetres that would be about 12 foot or writen as 3.660m if a 4×2 would be 100mm x 50mm just leave the centimetres out and u will be fine

  25. Bob Demers

    I am Canadian, and grew up with the imperial system, back in the mid 70s our government tried to switch us to metric. 40 some years later we still use both system. My kids grew up in the metric system, and it was always a PITA when I asked them to measured something for me, they of course used the metric markings on the tape or ruler. I quickly fixed that by removing any measuring devices using both system, if it got metric on it, its not coming in my shop 🙂
    Today, im used to metric distances when travelling ( I no longer do the conversion in my head), and im used to my car speedometer in Kms, so much that when travelling in the state, I really have to watch my speed. both KMs and MPH are shown on our speedometer here, but I whish it would simply switch back and forth as I cross the border :-)Im also fully converted in temperature in Celcius, but as far as woodworking, ill stick stubbornly, if I have to, to my imperial system thank you.

  26. Cyrus

    This is one of my favorite topics and perhaps I should reflect on a more complete reply. But let me say this :

    1. I use metric, everything is a mm. This is very simple and intuitive for all my work. I have metric measurements on all my tools and tapes.
    2. I am in the US and I grew up here, so I should be biased to imperial system, but in chemical engineering school i learned that my computation was more accurate and faster working in metric. Try a complex unit like viscosity in imperial — no thanks! Its possible but more error prone. (pascal * seconds vs pound force * second per square foot — yuk)
    3. I do end up using both and communication with the wife (the boss) who approves project plans means conversion to imperial as needed. Her intuition is growing though – that’s gonna be a 140mm moulding…

    I do really like the lack of fractions and “everything is a integer”. I use mm exclusively. In line with John’s comment — I wish I had better tape measures, but I have never had a problem with the combo ones I have. Maybe I will look into a few metric only tapes, I tossed my imperial only ones. Fractions are more error prone and are central to accurate measurement in imperial. Always integer answer is a huge advantage to me.

    • Sk Adrian Ux

      yeah cool story bro

    • kiwi-ian

      Yup. Can’t disagree.

  27. Cyrus

    Oh, and at work for me, everything is a nanometer or a micrometer.

  28. Martin

    I’m have not read all the comments in this discussion so I may be repeating an earlier comment. However, I learnt that the metric system uses Latin terminology to name the various divisions of lengths, with metre being the name for the basic unit of length. Thus millimetre is one thousandth of a metre, centimetre is one hundredth of a metre and decimetre is one tenth of a metre. (Other terms relate to lenghts beyond metre.) It seem to me if the term decimetre were brought back it would readily define a lenght common in wood working.

  29. John

    As some others have already said, the unit of measure that you’re pining for is the DECIMETER. Now, I live in the US so I do not use the metric system on a daily basis. However, in school when we learned about “SI” measures we discussed all of the different divisions or graduations. The meter is the standard unit of measure. Centimeters are one division of a meter (1/100th). There is also the prefix deci-, meaning a metric unit of length, equal to one tenth of a meter.

    Not being familiar with metric measurement devices I do not know if they make tape measures or rules with decimeter graduations? It would only seem logical to me that they did considering that the metric system is a ‘base 10’ system of division.

    Just my thoughts.

  30. JimG

    It seems theres a 3rd alternative, not being bound to any particular scale. In this case the piece is laid out proportionally w/i a max H, W and T. That is, sub-assemblies/pieces are some proportion that fit harmoniously w/i the biggest picture and surrounding/adjacent parts. In this way dividers are all thats needed and the scale ‘floats’ w/i the needs of definition.

  31. Tim

    I haven’t read all the comments, but I use both Imperial and Metric – I basically ‘have to’: metric is fantastic for small lengths – easy to do the math and accurate. Imperial does not lend itself to quick and easy math – 5 and 7/8ths + 3 and 4/64s….but that could just be me!

    Imperial is great for large scale objects – a sheet of 8′ x 4′ is so much easier to deal with, than 2400mm x 1200mm metric equivalent…it’s even easier to speak it !

    So, laying out a patio deck – feet and inches; building a workshop cabinet – mm all the way!

    Great blog !

  32. Jonathan

    Interestingly I came across a fascinating video on you tube which features traditional compagnon charpentier Nicolas Touchfeu. In it he shows lots of cool stuff such as doloires, hewing axes, holdfasts, bisaigues, and (relevant to this thread) a traditional Carpenters ruler, which looks to be a simple small lath of wood scribed across with engraved lines to describe “pouces” and what look like “demi-pouces” at one end. He does actually say “un pied consiste de douze pouces” (“a foot consists of twelve inches”)
    Cheers Jonathan

  33. Paul

    A never-ending argument…
    For what it is worth, a few asides.
    I am English, and now live in France. I am of an age where I was taught & “feel” feet and inches – also pounds, shillings & pence!!
    In France, the pouce is still understood as a unit of length, as is the livre (pound) – these dating from their official use until the end of the 18th century.
    Taps here are in inches!
    A Bob is almost equal to a millimetre (0.042″ : 0.039″).
    With small lengths, either metric or imperial is fine, but for longer lengths in feet+, imperial has an advantage.
    Remember though that our predecessors didn’t have rulers or tapes. Proportion, fractions/multiples of a unit length, etc..
    I could muse on, but enough for now.
    Like the blog/site – very instructive.

  34. Matt

    I’m 25 and I tend to use inches for things up to 2ft and meters over that, which can get very messy as sometimes I use feet and inches all the time and others I use mm. I am slowly stopping using mm as I find it easier to see feet and inches in my head. I blame reading lots of old woodworking books.


  35. Steve Bennett

    Hi All,
    A lot of it relates to how you see your own measurement!, By that I mean when we thinks, design and imagine the furniture for example we want to buil, we think about it in terms relative to ourselves.
    So I’m 6ft,1, easy, so 73 inches, hmmm ok, so 185.4 cm, ok getting higher now… or 1854mm,, nope lost it…
    If I want to build a table or chair or workbench for my height, is’nt it easier to think about my height, armspan etc in a measurement Im familiar with?

    Just also want to say, the videos are great, can’t wait to build my own clinched nail chest and have used some of the ideas and techniques on rebates in the wall cabinet for some other projects.

    Steve B,

  36. Erik L

    Hi all!
    In Sweden, where I live, most things have been measured metric, but only the last twenty years or so wood dimensions have been strictly metric. Growing up with woodworking father and grandfather it still seems natural to think about boards as being 2″8, although I have never heard other than metric lengths, regarding carpentry given in meters and centimeters as 2(m) and 87(cm). Nowadays sizes of windows and doors are given in decimeters as 10×14.
    Originally most countries had their own inch. The Swedish one was 24.75mm compared to the imperial 25.4mm. For quite a long time these three systems were used parallel as: Works inch, English inch, ce timeters

  37. daniel j. bonds

    This is Daniel, I am from Colorado, USA. A little background info here . Inherited some woodworking tools
    recently and decided to try making this a new hobby. Considering that my previous experience with wood are campfires….it has been a fascinating and challenging endeavor so far. I have been a metal fabricator for nearly 30 years. During this time I used a decimal/inch reading tape (Stanley PowerLock 33-272). This tape divides by both imperial and decimals. I have taught many a novice new to inches how to decipher inches, by using decimals; instead of 1/8,5/16 or 3/32 it would be .125, .312 and .094. This they were able to grasp faster because an inch is divided into tenths and hundredths. On the flip side I have been working in decimal inches for so long I have forgotten how to ‘speak’ in eights…having to learn that all over again.

  38. Mark Rasmussen

    This American, who has always lived in an Imperial World, has quite happily and successfully converted to using the metric system. I find the math much easier, and millimeters a better small unit than sixteenths or thirty-seconds or sixty-fourths. Not having been raised on meters, though, has allowed me to make effective use of those “decimeters” that I did not realize were not in favor. But really, who wants to add 3/16 to 7/64, subtract that value from an inch, and divide that in half? I’ve actually had to do that, by the way.

  39. Leonard

    Ha! This topic never seems to lose its appeal. I grew up with Imperial, did all my schooling in Imperial and did year 1 and part of year 2 of my mechanical engineering degree in Imperial. Metric was introduced in year 2 and was standard for years 3 and 4. I couldn’t toss the Imperial system fast enough, and I’ve never looked back! I find Imperial completely unintuitive, a mire of the most ghastly relationships and just plain dog awful confusing. I detest, loath and despise the Imperial system, so it was a hell of a shock when I moved to New Zealand 10 years ago to find people still speaking feet, inches, mph …… (quick break while I go wash my mouth and mind out with soap). They have (by the way) become a lot more civilised as the old guys die out, taking their system of measuremnts with them.

    Apart from the “I prefer it because I know it” view (which actually makes sense, because we work best with what we’re comfortable and familiar with) not one of the perspectives on ratios, intuitive sizes, etc, mentioned in the comments make any sense to me. I only work in mm and m, changing depending on the size and degree of accuracy needed. A sheet of plywood is 1.2 x 2.4 (see how smoothly that rolls off the tongue?), but if I’m cutting it into accurate pieces, it’s actually 1220 x 2440 (rolls just as smoothly off the tongue). Need to measure a deck? No problem …6 x 5.5 (metres of course). Measuring the shelf spacing? 325 (do I even need to include mm?).

    I think you’ve figured out where my preferences lie. It would take dire threats of harm or lots (and lots and lots) of $ for me to use Imp … Impe … There; I can’t even force myself to type it.

  40. John Starkie

    “Visual cue” not “visual queue”.
    Although yours brings some entertaining pictures to mind!

    A tenth of a metre (10 centimetres) is a decimetre.
    Used less often than a drawknife.

    The overwhelming advantage of Imperial over metric is that you never accidentally misplace the decimal point.
    My son (brought up on metric, but builds wooden boats as a hobby) delights in mis-pronouncing “eleven thirtytooth”.

  41. Russell

    Grown up with imperial and find feet and inches much easier to visualise. If a customer is sending me measurements I’ll have them send metric and imperial so I can double check.

  42. Ilya Gromov

    I’m late to this party but here’s my problem with imperial… it’s always a quarter, or a third, or a half OF SOMETHING (an inch). SO it’s always a part of something bigger. In metric system it’s always the direct measurement – 100 or 234 mm. You don’t have to think about the number as something in relation to something else.
    To me it’s just more direct and straightforward. But this problem only exists for those who try to go from one system to another. It’s totally nonexistent if you only use one system.
    But the only reason I’d use imperial system is if I was working with imperial measured tools 🙂

  43. Dave

    I recently retired so served my time in imperial. As I progressed through my working life I had to adopt the metric system, I had no choice all the drawings and instructions were in it, but I always found it difficult because I couldn’t relate to it. If something was 18 inches or 2 foot 6 inches, my brain knew exactly what that was, but 460 mm meant me looking at my tape. Given too that I spent a big chunk of my time on a self-employed basis I was left to work using the imperial system more than had I have been working for an employer.
    Recently fitted a new kitchen and found myself using the metric system when setting out but reverted back to using inches when cutting the worktops and plinths to length.

  44. Rav

    My height is 5’8″
    Distance from London Ontario to Toronto about 200km
    I grew up using both. If I need to do any kind of math I switch to metric. Well… Math that I know I will have trouble with in imperial. I’m not strong on fractions.
    Short distances imperial and larger metric.
    I wish metric fuel consumption was kilometres per litre just like MPG.

  45. Nicolas

    Metric System should be everywhere. Living in the United States is hell for me, a European.
    Unfortunately, Americans are so stubborn and ignorant, that they don’t care that whole world already uses Metric System, because it “for all people and all times”, and just normal and convenient.
    I ask all people who really care, let’s make Metric Revolution in the US and physically switch everything to Metric Units. Let’s remove outdated units from here, otherwise the country can collapse.
    Only because of the US, we still have stupid inches as measurement of screen sizes around the world. Unbelievable.
    It’s 21st century already! Why do we still have outdated imperial system in the world? Crazy.
    Thank you for reading my plea. I love you people. All the best.

    • Glen C


      Do I even need to point out what’s wrong with what you said?

      If it’s too hard, then perhaps you should simply go back home.

  46. Mike

    SI units – get with the program America!

  47. Andrew Frudd

    The centimetre is not a scientific unit which is why it is not used in construciton/engineering. Your point about 1.2m/120cm/1200mm being hard to find is true, especially when the number is a lot more randon. Incedentally, there is a practically unused unit in between, the decimetre, 12dm being 120 cm.

    I find it really hard to measure things in fractions of inches – to me measuring 6 9/16 inches is so cumbersome compared to 167mm. But then I think this is due to what I am used to. I cant look at the divisions in the inch and know what they are without counting the segments – probably because I have not practised it so it isnt intuitive. With mm you tend to have a bolder mark every 5mm so at a glance I can read it off.

    • Matteo

      the conversion between km,m,cm,mm is seamless, you just move the decimal point, no conversion or calculator needed

    • Andrew

      Could you explain in which way you consider the cm to not be a “scientific unit”?

      The National Institute of Science and Technology seems to disagree –

      Perhaps you wanted to say that its a unit which has generally not been adopted by a specific industry that you are familiar with?

      • Chris

        In all fields of engineering and science the SI-base units are used (for length that is the meter). For larger or smaller numbers, the approved step size is 3-powers of ten (‘orders of magnitude’): kilometer, meter, millimeter, micrometer, nanometer. Centimeter and decimeter are acceptable and find common use in households, but not in scientific and engineering practice. At least not in the rest of the World. 😉

  48. Matteo

    Article makes no sense. The only reason why the imperial system is still used is because people learned to use it and don’t want to change.

    the metric system is everywhere else in the world, literally. Makes it easier to think in proportion? what the hell are you talking about?

    It’s harder to use the metric system for longer distances? lol have you use m, dm, km? seriously people it’s base 10.

    The imperial system is still going because it’s very approximative and people feel comfortable using it, but it’s a nightmare if you go outside of the little bubble you built yourself

  49. Marika

    Just like to let you know that 10 centimeters is 1 decimeter. So you are wrong. I can much more easily visualize 1,24 meters than 49 inches.

  50. MetrikUberAlles

    Millimitres are best because: German and Japanese precision. Both have world records for precision consistently the past 100 years the UK and US never came close to.
    Second- some US imbeciles may claim “Yeah well, the Military and Nay-saw use millimetres but I never done saw me a ruler with a scale smaller ‘an a 64th of an inch! USA USA USA”
    Most SCHOOL rulers have HALF millimetre markings, shop precision rules have quarter millimetre- where a 64th inch = 0.39mm, a half millimetre is 0.5 mm, and a quarter is 0.25mm (not hard to find if you use a magnifying glass), which is 1/128 inch.

    The largest ever single piece cast iron was accurate within 1/10mm (1/254 inch)-
    Germany undertaken by Seidelkamp namely Ralf Griesche and Dr. Uwe Stein. Most accurate bearing record holder currently NSK Japan, previously SKF and Schaeffler of Germany. Most accurate hard-machine lathe- Mikroturn Germany. Most common global precision measuring tool company- Mitoyu Japan.
    Most accurate CNC- FANUC Japan accurate to 10nm- that is 20 Silicon atoms.. CNC regularly exceeds 1/10 “thou” is 0.0025 mm accuracy.
    10 nanometres= 20 silicon atoms= proof metric system corresponds well to atomic units.

    The empirical evidence exists. Nothing rivalling the precision of metric ever has been created using imperial. Even the UK threw it away- because it is a useless CUSTOMARY unit, like the Spanish foot (278.6mm), the Dutch ound (494 gram), the French vergee (1277 sqm), the rod or Ruthe which varied from city to city in each German Princedom. Mindless parochialism.


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