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Converting Millimeters to Fractions

61K views 112 replies 68 participants last post by  t3steve 
#1 · (Edited by Moderator)
Okay, so it's a slow day at work, but this has been a pet peeve of mine. I often run across a measurement given in millimeters, and wish I had a handy reference to convert that number into fractional inches.

There are a lot of charts and calculators online that will give you decimal equivalents, but nothing I could find that will quickly tell me that 17mm equals pretty close to 11/16ths. So I used my Excel skills and some free time to come up with my own. You can get it here:

http://www.loyno.edu/~cbmarsh/mmtofraction.htm



I have included columns to get you to the nearest 16th, 32nd, or 64th, depending on how precise you care to get. The PDF version will be easiiest for most of you, but I've included a link to the Excel file as well, in case you want to monkey around and modify it to best suit your own needs.
 
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#4 ·
Thanx! a good reference to keep around….. now if everyone would only work in metric…. we wouldn't have these problems to begin with would we? lol…

sorry, but metric just makes sense, and working in fractions is a pain in the a$$ sometimes.
 
#6 ·
I couldn't agree with you more. But the old inches and fractions system just wont die.

If I'm not mistaken, it was something like 30-40 years ago when it was officially announced that the U.S. would be going to the metric system. I guess the wheels of progress turn slowly, huh? :)
 
#10 ·
I definitely appreciate your work on this but I won't be using it. sorry. Canada had the metric system forced on us a number of years back and one thing I have learned in that time is to never convert.
If it's in imperial measure use imperial. If it's in metric use metric. The cost of appropiate measuring instruments is very low compared with the aggravation and inaccuracy of converting.
Just the opinion of one ticked Canadian. It wasn't broken and didn't need fixing.
 
#17 ·
Doug, do we have to say anything nice about Bill Gates? (I do love Excel, though. I've used it for years and am still finding new things I didn't know it could do.)

Callum, be careful using that cell phone in the shop! :)
 
#21 ·
John, that's a good site. I have a little conversion calculator on my desktop that does the same thing also. But for me, the missing element that I always seem to be looking for is the mm to fractional inches conversion. I could not find that on the internet anywhere. (I'm sure someone will provide a link to prove me wrong.)
 
#22 ·
I had a guy once told me he wanted a board ripped two and two thirds inches wide. I told him i couldn't help him because it wasn't on my ruler. Lol

As for metric. I admit its a better system. I think the answer to why we haven't converted can be found in Americans general distaste for most all other things European. Now i've stepped in it!
 
#23 ·
How un-politically correct of you, Miles!

Besides, we don't dislike everything European. Particularly those French and Italian women come to mind (at least the ones who shave their underarms).

There…. now I've insulted Europeans and feminists in a single comment. :)
 
#24 · (Edited by Moderator)
Shame on you Charlie, now we are having the metric -v- imperial discussion again ;)

Too bad we don't have 12 fingers. 12 is a more natural number for archetectural measurement since it can be evenly divided in so many ways. 10 sucks since it can only be divided evenly by 2 and 5. It's multiples are just as bad. 20 can only be divided by 2, 5 and 10 while 24 can be divided by 2, 4, 8, and 12 which as you can see are all themselves divideable into halves and quarters because they don't have that ugly 5 in the middle.
 
#25 ·
Nice to see a comrade step in it with me!

As for converting metric to fractions. You really get a skewed result. Because theres too much rounding off going on. Lets say you decide 17mm is 11/16ths. Then when you multiply 11/16ths by say…50…you get a far different answer than 17 mm x 50.
Getting to intimately know fractions by their decimal equivalents is the way to go for math purposes. After years i pretty much know the decimal equivalents of all fractions from 1/16th to 15/16ths in my head.
 
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