# Inches Are Written With Fractions…Not Decimal Points

Okay, pet peeve coming up! How do you write inches? Let’s say we’re talking about a painting that’s five and a half inches by seven and one eighth inches. Do you write 5 1/2 x 7 1/8 in? Or do you write 5.5 x 7.125 inches? I hope you write the former rather than the latter. Why? Because inches are written with fractions!

So that’s my pet peeve in a nutshell. (WARNING…some math stuff coming up…😳)

When we use a decimal point, we’re talking about numbers with a base of 10. So 0.5 is five out of 10, 0.7 is seven out of 10, 0.01 is one out of 100.

With inches, we’re talking about a base of 2 (rather than 10). Inch fractions use denominators that are powers of 2 and go up to a 64th of an inch. So fraction denominators will be 2, 4, 8, 16, 32, 64 (eg 1/2, 3/4, 3/8, 5/16, 7/32, 11/64). You can see there are no tens involved!

Think of a ruler that’s a foot long. It’s made up of 12 inches. (Still no tens to be seen!) Each inch is usually divided into 16 parts. So we can have 1/16 of an inch or 5/16 of an inch. If we have 4/16 then that fraction becomes a 1/4. If we have 8/16 that becomes a 1/2. We try to make the lowest equivalent fraction. (Remember back to math class? That may be difficult I know!) Anyway, you can see we’re talking about fractions. Not a decimal point in sight.

So when I see someone write “6.82 inches,” I think, What does that mean? What does that look like? I can’t find it on a ruler so I have no visual picture of what it is.

Centimetres on the other hand are divided into 10. A ruler will have each centimetre divided into 10 parts (10 millimetres). So if I see 6.7 cm, I can visualise that on a ruler. The decimal point shows seven out of 10 parts.

You can of course create a decimal from a fraction. Certainly, fractional inches are limited whereas decimal inches are limitless. BUT as an artist rather than an engineer or a person in construction-land, I don’t need limitless. I need a measurement I can visualise. And traditionally, inches are written with fractions and I can visually conjure these up as I’ve been brought up using inches.

So the question is, why do people write inches with a decimal point? Well it’s a heck of a lot easier that’s for sure! Just pop a decimal point in and voila!

(A side note: I bet many of those decimalised inches aren’t even correct! Want to know how to make a correct decimal out of a fraction? See the video I’ve posted at the end.)

Fractions are a right pain so it’s easy to understand that a person might want to avoid them. But the reality is, inches come with fractions!

Gawd that’s an awful lot of numbers for an art blog but I needed to get this peeve off my chest! So let’s look at a couple of images.

I’ve been preparing for our Looking at Art session in the IGNITE! Membership (where we look at paintings related to the month’s theme) and I’ve been cruising around the Art Gallery of Ontario. Measurements are written both in centimetres and in inches and each notation looks quite different – the centimetres are written with a decimal point, the inches with fractions.

Here are a couple of examples:

You’ll find that some museums give dimensions only in inches or centimetres rather than both but they’ll be written as they should be: inches are written with fractions while centimetres use a decimal point. (Some galleries note the measurements in millimetres which means no decimal point…just numbers.)

I think it would be a great idea to embrace the metric system as there are NO fractions (which are pretty ughy so it’s no wonder there’s a trend by artists to write fractions of inches with a decimal point). In the metric system, there are only whole numbers. But for some us brought up in the feet-and-inches world, it’s harder to visualise measurements in centimetres (and metres and millimetres). Still, I encourage you to move into the metric world!! I’m trying.

In the meantime, please, if writing about dimensions in inches, use fractions rather than a decimal point!

Right. That’s me off my soapbox. I’d LOVE to hear your opinions about this whole fashion of writing inches as fractions. Do you write inches with fractions or a decimal point? Let me know your thoughts!

Until next time,

~ Gail

PS. Here’s the Hare Study as a whole:

PPPS. Here’s a great wee video on how to go from fractions to decimals and back again!

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### 69 thoughts on “Inches Are Written With Fractions…Not Decimal Points”

1. Don’t you think it would all be easier if USA, Myanmar and Liberia all quit using the Imperial system of measurement and changed over to the Metric system? After all the entire rest of the world uses metrics! (Thanks for the chuckle your amusing rant produced!)

1. Well yes…
And I had no idea that it was only three countries left in the world using the Imperial system!! Thanks for that info.
(Glad you got a chuckle from my rant 😜)

2. Absolutely! Oz went decimal (including miles to kilometres, pounds shillings and pence to dollars, ounces and pounds to kilograms, etc) in 1966/1967. It was awful for a fortnight, then it was ridiculously easy, like we’d been given an A instead of a D. For a while both versions were given then that just stopped. The thing I notice in the art world is that we’ve got standard sizes, like A4, A3 etc which everyone recognises instead of quarto, foolscap, letter etc. And you cannot type fractions properly so it takes longer to figure out what 5 3/8 means or 7 3/16 — Fortunately I inherited a number of long wooden rulers used in dressmaking so I have to put a metric ruler next to an Imperial ruler and try and get close to the size. Reminds me of the gun issue…it is and will continue because it just is regardless.

1. Thanks Suzanne, for sharing your own journey from the Imperial system to Metric. I think having the committed intention to change helps enormously as does a time of transition and then an end to that so that the change can be made completely.
I would say to your note that we have standard sizes like A4 “which everyone recognises” that that’s not actually the case (sadly). For instance, although I’m fairly ‘metricated,’ I have no clue what an A4 etc looks like. I guess it’s time to take steps to learn that!
And…I change inches to centimetres the same way you do – ruler to ruler lol!

3. You touched on the reason why inches sometimes have decimals instead of fractions, engineering. Also computing. I work at a hardware store and if I cut a piece of glass to 37 5/8 inches by 23 7/8 I have to enter the numbers in the point of sale as a decimal. It’s annoying but I just suck it up. When converting from metric to imperial you get far more accurate conversions using decimals as well.

4. Yes, and the author is also confused. “five and a half inches by seven and three eighths inches. Do you write 5 1/2 x 7 1/8 in? Or do you write 5.5 x 7.125 inches? ”
Well, no, because seven and three eighths inches is 7 3/8, not 7 1/8. If you are going to publish, get it right.

Interestingly, US American engineers convert inches and fractions into decimal, make the calculation, then convert back to the approximate nearest fraction, making everything quite inaccurate. It would be far better to just remain in decimal. I worked for a year in the USA at a biology research lab, and everything was done using international SI units, including temperature. This is because if they don’t the rest of the world will ignore USA published research as unusable.

1. Hah hah. Well spotted Egdir! And I can hardly believe I missed that error. Thank you and now fixed.

And thank you for your additional comment regarding the practice of US engineers to convert and convert back. And yes, far better to remain in decimal!

1. Fractions & inches are both representation of a whole not 10. As someone who owns a trophy shop and often has to create art or speak to an engraving machine digitally I do so in decimals. If I’m asking someone to cut something w a ruler I say it in fractions. I think both expressions are quite useful when it comes to measurement.

1. We didn’t sleep in class when we were taught how to find the least common denominator. Also, we are proficient in both systems and generally have no trouble working in either.
If you have inch fractions that have different denominators, you can just double the numbers in the smaller fraction as many times as necessary to make the denominators the same, and then just add them together.
5/8 + 37/128
10/16
20/32
40/64
80/128 + 37/128 = 117/128
You’ll probably never need to be that precise so the steps are typically even less. But the fractions are way more precise than millimeters

1. YES! Exactly.Thanks Nathan for reminding everyone how to do this.
But you wouldn’t say 0.117, rather you’d say 117/128.
It’s the use of a decimal point with inches that drives me a bit crazy lol! Fractions are fractions!

1. Oh yes Helen! I know it makes total sense to those brought up with that measurement but for many of us it’s…huh?? But it does come out of a metric measurement (and weight) system. Here’s a link to some easily digested info on the origins. Apparently only Canada, the US, and much of South America don’t use the A series standard! Guess we better get learning!

1. Thanks for this link Gail. Very interesting and so straight forward too. I had no idea it was so widely used. We need to get onto it!

2. I so totally agree! I’m in Australia, where we use the decimal system with centimetres, but still also use feet and inches, and even though our rulers and tape measures have both, decimal on side and imperial on the other, decimal points using inches are hopeless. If you have to use decimals, give us cms then its much easier to see the alternative instead of having to somehow work out an inch divided into 10.

1. I think it’s even more difficult, like you say Caroline, when one system IS the system yet the old way remains in play which just confuses everything! And yes, decimals belong with centimeters not inches!!
(Did you have a look at the video? Really cool. It shows an easy way to transfer back and forth…not that I’m encouraging decimalized inches!!!)

3. I grew up (until the age of 12) with the metric system of measurement. When we immigrated to the US and the imperial system it was seamless, and I have always preferred the imperial. I worked in industry where our measurements were in tenths of thousands of inches. No problem. Don’t know about Canada, but I see many artists in the UK post their dimensions in inches, so there’s that. But there are times when it would really be nice if both types of measurement were given – as long as the beauty of the art is there.

1. Hey Steve, thanks for sharing your journey with the two systems. I’m curious to know what line of work uses tenths of thousands of an inch – that’s mighty small!! Yes, I’d say Canadian artists mostly post with inches even though we are a metric country. We have mostly changed but not entirely.

I agree that it would be lovely to have both measurements all the time but that takes time, of which we often have so little! The main thing is to have a measurement (height x width please) AND to write inches with fractions rather than with a decimal point hah hah!!

4. My first measurements were in Imperial…born in UK. Then came to Australia when the ‘change over’ to Decimal took place I 1966.
So I can see both sides!
Gail, enjoy Tuscany this year and say Hi to Rafaelle!

1. Hi Christine! Yes, I also see (and use) both systems. My rant is really about HOW inches are written 😬

I’ll miss you in Tuscany! Soooo looking forward to going again. (And I’ll have the earrings that you and Val so kindly gave me!)

5. We have been metric here in New Zealand for years so both measuring systems come easily now. Just takes a bit of time to get familiar with the decimal system. Actually it is much easier to use than imperial once you do!

1. Hi Penny, super you can easily switch back and forth. I think the decimal system makes much more sense to use but my rant is really around using the decimal system with inches!

6. Also thanks for the chuckle.
I grew up with the imperial system and used it professionally and then, more than 50 years ago, came the metric system.
Because of old documents and the ubiquitous American influence we in South Africa still have to think in terms of meters, (metres?), feet and inches, decimal feet, Cape feet (!) without inches, roods, kilometers , miles, yards and now I am getting confused.
I am going to find a clean sheet, (forgot the size, now), and some pastels.

7. Living in the states, I’m accustomed to feet and inches, BUT, once I started framing my paintings, I tried to use the metric system and cm’s. It seems to much easier when it comes to measuring. The US may want to stand firm, but I’m finding that in the Art world, the metric system is where it’s at, so I’m trying – it’s never too late to learn.

8. I think sometimes it is because you have to input a size (of a painting, say) into an e-form and there are no suitable fractions on the device you are using and if you used normal size numbers with a “/“ it could be/has been misconstrued. This is in the UK where we are metric, but not completely!

9. AND to add to your rant, it annoys me that the UK and USA still use imperial measurements because when buying materials, the canvases or panels are NEVER the same size as the French ones! I’m English but live in France so I’m totally converted to METRIC!!

10. Nice rant, but really the problem (and my favorite rant) is the continued use of inches and feet for measuring. I spent many happy years in Germany and it took me no time at all to adopt and visualize the metric system. You don’t convert measurements, you just use the other ruler and soon enough you will visualize what 30 cm or 8cm look like. I’m glad there are rulers with inches on one edge and cm on the other. I HATE THE IMPERIAL SYSTEM.
Thanks for listening to my rant.
Btw, I use fractions when I have to use inches. Too much of a bother to convert.

1. Hah hah …love your rant Dana! And yes, converting to metric is easy when you put your mind to it…but that’s the crux of the matter – you need to want to do it. And it helps when those around you are using it too! (It’s easier to learn a new language when you hear it all around you!) The main thing is to be able to visualise what say 20 cm looks like or 20 inches.

So glad to hear you use fractions when ugh, you need to use inches.

2. Hah hah …love your rant Dana! And yes, converting to metric is easy when you put your mind to it…but that’s the crux of the matter – you need to want to do it. And it helps when those around you are using it too! (It’s easier to learn a new language when you hear it all around you!) The main thing is to be able to visualise what say 20 cm look like or 20 inches.

So glad to hear you use fractions when ugh, you need to use inches.

11. Being in the US, I’m used to feet and inches, BUT when I started framing my paintings, I started working with the metric system – it seems so much easier. So I’m trying!

1. Well good for you Lori!! Although it feels strange to those of us brought up on feet and inches, I also think the metric system is easier to use. And if we accept and commit to change (rather than resist it), as you’ve done, it is easier to “get!”

12. Thank you!! I learned in inches also & have no clue how to use cm………same with miles vs kill. ….and I don’t want to try & learn it all over again at this point in my life – just not interested!

13. I am currently more into woodworking than art ( temporarily I hope) and watching the predominantly American content on YouTube. Several people have made impassioned videos about why the imperial system works better for them. The main thing is that halving or doubling measurements are much easier by simply changing the denominator of any fraction. For example if you want half the thickness of a 3/4” board you multiply the denominator by 2 giving 3/8” or twice the thickness of a 3/16” board divide the denominator by 2 giving 3/8”. A good steel rule has measurements down to 1/64”. Try that with a 753.3mm board and see how much longer it takes. I don’t think I have ever seen a woodworker mix inches and decimal points which would get mighty confusing.

1. Hi Eddie! Thanks for your take on the whole thing about inches and centimetres! It’s funny how my peeve has turned into something much bigger via all the comments. Love it!
How interesting about the ease of doubling or halving measurements in the imperial system. Fascinating!
Glad to hear inches aren’t used with a decimal point in woodworker land 😜
And….hope you can fit in more art soon. (Gotta ask…why more into woodworking these days?)

14. When it comes to pastels How can you measure the wonderful immeasurable beauty of timeless art. Best wishes to you Gail in the Tiger year for bringing us all the pastels tips ,insights and color ideas. Pastel on with joy !!!

1. Hah hah Mark…thanks for your lovely comment and good wishes. And the reminder about the beauty of art 😁
(And embarrassingly, oooooh, I hadn’t realised it was the Year of the Tiger – rrrrrroar!!)

15. When measuring something with a tape with imperial and centimetres, I use which ever is the easiest to read!!! Also as a sewer/quilter, inches are mostly still used. DH uses millimeters in metal work (that where the fine work comes in 1/1000 etc) and has an aversion to centimetres.

1. I had to laugh Nola – that makes perfect sense!!
And interesting about a preference for millimetres over centimetres – I’m not keen cos the numbers can get reeeeeeaaaalllly large hah hah 😂
(DH?)

16. Gail,
Thanks for the math lesson. I had no idea inches were based on 2.
When I came to France 55 years agoI had to get into the metric system, but I still have trouble with milliliters and centileters etc.
While we’re on the subject of fraction, the ONLY thing iI recall from high school chemistry was that when converting Centigrade to Farenheight, or vice versa, forget the 9/5 fraction thing. All you have to do is:
F= 1.8 C + 32.
Don’t let the math get you!
Nancy

1. My Dad keeps telling aboutthe temperature conversion too, that’s all he recalls. He tells me, then I forget lol!
And I won’t let the math get to me

17. Yes! Finally someone after my own heart! I was a graphic designer for many years and began using metrics decades ago. In my case it was necessary simply because you can’t use fractions with a calculator! In particular i used centimeters and millimeters to calculate ratios in enlarging and reducing. When Quark (nowadays InDesign & Illustrator/Photoshop) came along i went into preferences and set my measurements for centimeters and never looked back. Discovering metrics was a joyful revelation! Over the years spending time painting in Europe I now use metrics for volume too. I feel a kinship with those who are metric-minded now! By the way, thanks for your blog!
Larry Pahl

1. Hi Larry! Thanks for sharing your story about converting from the Imperial to the Metric system!😁 It’s such an obvious factor …about not being able to use fractions on a calculator 🤦‍♀️ It may well be this fact that’s led to the use of a decimal point with inches.

Here in Canada, we are mostly metric. I mean, we ARE metric but when it comes to weight it seems some still cling to pounds and ounces, especially in the grocery store! I think it’s more difficult to make the change completely when the shops show the price per pound in large letters and then in kilograms in small letters. Grrr. Of course when you get to the till the p rice is in kilograms!

Thanks for sharing your joy in the Metric System!

And thank you too for your blog appreciation 😊

18. Gail, you make an excellent point. You are absolutely correct that the metric system does not blend well with the imperial system. All this made me think of my pet peeve which is related to framing. When a person buys a mat at a store the opening measurement will say , for example, 4 by 6 inch opening. But, the opening is really 3 1/2 by 5 1/2 inches. Well, if we price art on the square inch which measurement should we use?!!

1. Hah hah Cynthia! I feel your agro about this and yes, Why is it that way? I guess the bevel edge takes something away but not a whole half inch! It’s like 2 x 4s in construction… they aren’t that measurement!
Sigh.

19. My favourite story about disasters caused by the conversion of Imperial to Metric is when NASA lost a \$125 million probe to Mars because the navigation team at the Jet Propulsion Laboratory used metric measurements whereas the company that built the space craft, Lockheed Martin Astronautics used imperial measurements. When the Jet Propulsion Laboratory was entering their navigation data they used the acceleration data provided by the construction engineers which was in imperial, but they assumed it was in metric.

The result was that the probe did not approach Mars correctly and it burnt up in the atmosphere.

https://www.latimes.com/archives/la-xpm-1999-oct-01-mn-17288-story.html

When construction company entered the navigation information they didn’t convert from metric back into imperial and so

1. Whoa! Cool (if unfortunate!) story! Thanks for sharing it Haydn. Just proves how much easier things would be if we were all on one system!

20. Dad was a civil engineer, I grew up doing drafting & design by hand. Knowing about mechanical and architectural rules (yes different scales (rulers)).

I currently work for a company doing computer aided drafting and design as well as 3D modeling. We work closely with European manufacturers.

Your pet peeve is one that does not effective us or our European counterparts, ever. It is not even about knowing how to convert or use online conversion. Our programs and software basically convert perfectly just by telling it metric or imperial.

Civil engineering software is the same.

Even when I cooked professionally this was not an issue. As recipes rarely called for conversions. Even if metric, scales do metric and usually there are measuring devices that reflect both measures.

But if it really peeves your pet, look to big corps and lobbies that thwarted past attempts at converting imperial to metric in the USA. Seems silly now as most manufacturers have facilities in countries using metric. Cost would be greatly reduced for a switch on an industrial level.

Not to mention politicians could brag at all the jobs created creating new mapping, road signs, etc (at tax payer expense of course)

And we all know the efficiency of the varying government bodies left to implement this change.

21. I can see that a lot of people have the same question. Why 5.4in? Maybe is mixed measurement system. Maybe is sign of a transition in the next 100years…. but not a official answer…maybe homedepot and lowes have one.
I think that US has an official answer for keeping imperial …somehow everything has to do both, but housing, roads, speed will be shown in Imperial.
I would add that writting in fractions, also can cause confusions depending how close are the digits, you always have to stop and make sure you are not reading part of fractions as an integer… 7 1/4… is not 71/4…
Just to add on paper size… in South America most of countries use A sizes…

I know that A sizes are used in the UK and other places. Good to know that that is the same with many countries in South America (I had no idea!).

22. Whenever possible, I try to force my trade into metric. Unfortunately, we weigh everything in pounds / oz, our fasteners are in inch fractions (except one furnace that uses a 8mm hex wrench to remove the door to access the components whose dimensions are given in inch fractions), etc. You get the idea.
All that being said, I carry an IKEA tape measure because it has both imperial and metric printed on the tape.

In the 80s and 90s, I would complain about the imperial system. I’ve been carpentering since 1985. The fractions used to frustrate me. Too many denominators. Then an old guy in the late 90s taught me the common denominator method. Now I use only inches and 16ths. So a seven and five eighths measurement is written 7-10/. Spoken, “seven and ten”. Totally simplifies the fraction condition, across the board. Today I focus mainly on bespoke custom furniture. Things need to be exact. I aim for accuracy within 1/256th of an inch. In the rough however, I’ll stop at a 64th. Which leads me to an even more simplified notation of the fraction, than even the fast common denominator….. that would be….. + & -. A plus, is 1/32 more than the numerator.

A minus depends on positioning. The minus before the plus [/-+means 1/64 more than the numerator. The minus after the plus [ /+-] means 3/64 more than the numerator. Or it can be noted “/–” meaning the same as the latter. Rather, referencing the next 16th numerator from the last.
So… 7-10/+- = seven and fortythree sixtyfourths or 7-43/64.
7-10/– = seven and 39/64. 7-12/+ = seven and 24/32. When I’m doing radius woodwork, I convert the 16th to .0625 and the 32nd to .03125 and so on, because I can get pretty darn exacting with the decimal. Then I round to the nearest 256th to get close to 3.5 thousandths tolerance as possible. After all, we can visually divide the space between two 16ths into 12 parts to aim at the 3.5 thousandths or 1/256 tolerance of perfection. This ensures that the radius I’m artfully and creatively joining the the angular pieces, join up flawlessly. Yes, I did construction (site, finish Carpentry) for decades. Cut/ glue and nail. But today, with the custom woodshop focus, I do much more creative artful projects. And use both systems. Actually I even employ Pythagorian system of 9 quite regularly as well… .Part of the art for me.

Yet when its all said and done, I always convert back to imperial 16th fractions because, well, 1) I’m used to it and I have fun with combining those systems in my own unique way. And 2) my material comes in quarter inch increments and my tools all register in inches…… including my tape…… that’s “measuring” tape for those artists that are not familiar with the art is Carpentry and joinery. 😇😁😉
✌🏾😎🙏🏾

1. Oh my gosh Richard – thank you for your detailed comment! You have my head spinning lol! I’m going to have to reread this a few times to let it sink in…
I know a lot of artists with a mathematical bent will enjoy your addition to this conversation.
I guess you don’t have a website where we can see your bespoke furniture?

24. For most people, using fractions is fine, carpenters use fractions. But machinists deal in thousands of an inch, fractions are not possible. As a retired mechanic in factories I had to use a lathe and a milling machine as part of my job functions fabricating parts. We use instruments like dial calipers etc. that are calibrated in thousands of an inch. Accuracy is crucial and fractions don’t cut it. Because of this when I measure stuff where I don’t need accuracy and could use fractions, I tend to still use the decimal point to donate fractions. That’s just the way it is for someone like me.

1. Hah hah. I sure have been getting responses from those who need to work in tiny measurements! Don, I appreciate your thoughts on this topic 😁

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