Which of these measurements is easier to read for an American?

28 comments

1. The fractions are easier to read, but the use of quotation marks to denote inches in that case tripped me up, I would rather see the abbreviation “in.”

   To your follow up question, these are definitely inaccurate, since 80% of an inch is not the same as 75% of an inch, and 40% of an inch is not 50% of an inch. Depending on what is being sold, this may or may not make a significant difference, but companies have been sued over falsely representing dimensions of things (like that famous Subway case of selling “foot long” sandwiches that were actually just less than a foot).

2. Depends on what you are selling and how important tolerances are. I would use inches and fractions of an inch if tolerances weren’t super important.

   But for anything with high tolerance use metric and decimals and also add feet and inches with decimal inches.

   For anything that is high tolerance there is probably a standard in the industry you can look up.

3. Your fractions need to be in multiples of 2.

   When it comes to dimensions smaller than inches – for things like wood and metalworking – we keep cutting the unit in half. So there’s inches, half inches, quarter inches, eighth inches, and sixteenths. Smaller than that, you can use decimals – one thousandth of an inch is a “mil”.

   There is no marking on a ruler for 4/5 or 7/10 of an inch. You’d have to round to the nearest 16th of an inch, if its within your tolerance.

4. Fractions that are multiples of 2 would be best. Halves, fourths, eighths, sixteenths, etc. You can go to whatever degree of accuracy you think is appropriate.

   For example my American ratchet set increments in 1/32nds of an inch. So 1/32, 1/16, 3/32, 1/8, …

5. We don’t use decimals with our length measurements because they’re not decimal. And most things are in powers of two for fractions, eg. ½, ¼, ⅛ and not, say ⅘.

6. Yes, I would consider those measurements inaccurate because they are. If I said 36 cm instead of 38 cm, you’d consider that inaccurate.

7. I typically prefer fractions when working with inches but in this case you aren’t using the standard fractional measurements so I’d prefer the decimal.

8. Maybe it depends on the industry and what type of product, but fifths and tenths of inches written as fractions seem weird to me. We typically use fractions for half, quarters, eighths, etc. I would write tenths as decimals.

   Whichever way you list them, the numbers should be accurate.

9. Our system makes it easier to divide things into 1/2, 1/4, 1/3. This is why it is better for everyday use – this is a much more common need than to divide things into 1/10.

10. Is it some type of engineering related business?

    If so, I would say go with decimal. It’s been the standard for engineering with feet and inches for decades. I haven’t seen fractions except on stuff from the 60s and older.

11. I was going to do this off the top of my head, but I decided to consult IKEA. If you’re going with the ” notation I think the fraction is the way to go (*7 3/4″*). If you’re going with a decimal then I’d say “in” (*7.75 in*). I’d say we’re more used to seeing fractions.

    I don’t like rounding when it comes to measurements because if I need something of a specific length/dimension, I’m counting on what’s listed in the specs to be accurate. *2.4 in* is not *2.5 in*.

12. If you’re framing a house or baking a cake, use fractions, but only halves, quarters, eights, sixteenths, etc. No tenths, thirds, fifths. Nobody measures stuff like that.

    If you’re making engineering drawings, use decimals. You decide how many decimals are needed based on how precise you need things to be.

13. What are you selling? I think that will determine how much a tiny fraction of an inch will matter.

    If we’re talking about construction materials then it probably matters more than if we’re talking about size of a screen or something.

14. Inches aren’t normally used with decimals, or fractions that aren’t multiples of 2.

    5.8 inches is more likely to be shown as 5 and 7/8 (which is actually 5.825), or 5 and 51/64 (5.796875) if more precision is needed. If a thing is actually 5.8 inches, it’s more likely to be shown as 14.7 cm (or 14.732 if the extra precision is needed.)

    For the follow-up, if I was buying a length of hose, and I paid for 5-3/4 but got 5.8 inches, I’d be OK with that. If it was 11/32 diameter, I’d expect that to be exact.

15. At first glance decimals are easier to read, calculating is loads easier using fractions. I am a fraction evangelist, they make more sense in a lot of applications. However, I regularly run into people who don’t realize 1/3rd is larger than 1/4th. It is a known phenomenon in the USA that people don’t know how to use fractions. There was a burger chain that advertised a 1/3rd pound burger and…it didn’t go well for them.

    [https://culinarylore.com/food-history:aw-1-3-pound-burger-failure-fact-check-are-americans-really-that-bad-at-fractions/#:~:text=During%20the%201980s%2C%20the%20owner,advertise%20their%20new%20Third%20Pounder](https://culinarylore.com/food-history:aw-1-3-pound-burger-failure-fact-check-are-americans-really-that-bad-at-fractions/#:~:text=During%20the%201980s%2C%20the%20owner,advertise%20their%20new%20Third%20Pounder).

    So, Americans are a little bipolar, for people who really know fractions we love them and there are enough of us that it is still used a lot. For people who don’t know fractions, they are useless if it is something like a ‘fifth’. So, at that point, just write how many fifths you meant as .2.

16. I work with a lot of measurements. The units on a standard tape measurer are marked at 1/2″, 1/4″, 1/8″, 1/16″, and sometimes 1/32″ or even 1/64″ increments. If you use decimals that’s fine, but I wouldn’t mark anything as 4/5″ or 7/10, that’s going to cause more headaches than 3.7 would. I would include the measurement in cm then approximate inches in parenthesis, rounded to the closest 1/8 or 1/16 of an inch.

    Size: 14.75 cm (5-13/16″)

    It’s pretty common for companies to include “nominal” sizes, as so many things are done in metric worldwide.

17. For your Followup Question:

    If the item in question is not being manufactured using US Customary units, just use metric. Advertising a 2.4″ item as 2.5″ is false advertising. Contrary to popular belief, we can understand metric units just fine.

    I use this to judge the quality of items purchased online. If I see goofy things like “2/5 of an inch”, I don’t buy it, because the seller clearly doesn’t understand the units they’re advertising in. If I see metric units and the product is made in UK, at least I can take the units at face value. Most Americans have a set of metric wrenches in their toolbox.

18. Fractions are easier, but they look odd because inches uses powers of two (halves, quarters, eighths, etc)

    I’d consider a 5.8″ or 5.7″ advertised as 5 3/4″ accurate depending on what’s it is. For most things, less than 1/16″ of difference doesn’t matter, and is within normal tolerances. If it’s specifically machined parts. Someone did sue subway because the footlong was 11.5″ or something, but that’s a significant difference at that scale

19. We divide the inch in half and keep chopping it in half to get smaller. So the fractions would be 1/2, 1/4, 1/8, and 1/16.

    None of the fractions you listed would make much sense as rulers or tape measures do not have those. You could round to the nearest 1/16th, but that depends on your tolerances.

20. It really depends on the product and the industry. You should really tell us that. It matters.

    For instance, if you’re in the porn industry full inches are the way to go. No fractions or decimals on cock length. Just round up to the nearest inch. Or round up two or three inches.

    In the construction/remodeling industry (including plumbing) everything is feet and inches and fractions of an inch. Materials are sold with those dimensions so things interlock smoothly. Plywood comes in 4 x 8 foot sheets.

    Paper and envelopes tend to use inches and fractions but you will commonly see “eight and a half by eleven” paper written as 8.5 x 11 and not 8½ x 11.

    More technically precise things might use decimal inches. 3.75 in x 6.4 in.

21. The decimal inches in your examples are way easier to interpret.

    5ths and 10ths? Those are metric fractions.. pretty much confusing the entirety of the planet with those 😉

    (Though you may see an occasional 10th of a mile on some road signs.. not to mention the mile markers are usually in tenths.. still, never with inches unless writing them as decimals)

22. Having worked in manufacturing in the design area, I am used to seeing decimal dimensions to the third decimal place.

    Where I worked, we used a design philosophy that from before WWII. Originally, this was in inverse powers of 2 (i.e. 1/2, 1/4, 1/8, 1/16, 1/32, and 1/64.)

    At some point, things were switched to decimal. So, using the above example, the dimensions would be 0.500, 0.250, 0.125, 0.062, 0.031, and 0.016, using rounding as .49 down and .5 up.

    There were some parts that were not rounded to the nearest fraction. If a part needed to be 0.735, it would be designed and built to that dimension. It would not be rounded to 0.750.

23. Like many others have said, use fractions that are a power of 2. State your precessions, but if it’s anything fine precision, just use metric.

24. It’s just like that business with shillings you used to have in the UK. We divide inches into fractions, sixteenths or even sixty-fourths if needed.

    I think describing 0.8in as 51/64in would be preferred even if it’s a little overprecise. Though perhaps your dimensions, once converted from cm, aren’t exactly 0.8in after all? As others have said, if tolerances are super important you should simply describe the item in metric units.

    The larger and more common fractions (1/2, 1/4, 3/4) have ascii characters that render them diagonally, which you should use if you can. Or [this](https://lights0123.com/fractions/) which is pretty neat.

    I also suggest using the abbreviation in for inches, not the quotation mark “.

25. If the size is critical, and yours fall in between standard US sizes, then don’t round them just to be fractional. It would probably be better to state the size in the metric unit, and then in parenthesis an “equivalent” size in inches. But if the size is that critical, then you might need to make one that’s actually sized in inches.

26. 5.8″ would not make sense. You would want to say, 5′ 8″ or maybe 68″ would be better.

    Don’t use use fractional feet to express inches.

27. If I bought something that was advertised as accurate to length up to fractions or decimals of an inch and it was wrong I would be put off. If it just said 5″ and it was 5.2″ I’d be fine. But as far as ease of reading, 5.8″ is the easiest for me on paper but in practice fractions of an inch work out better on a tape measure.

28. >Follow-up question – if a 5.8″ item was advertised as 5 3/4″ would you consider it inaccurate? How about a 2.4″ being advertised as 2.5″?

    Yes, that would be illegal in the US, as going against the standards of weights and measures.

    If you say something is 5.80 and it’s actually 5.75 (consistently) then you would get a visit from the gubbament.