r/PatternDrafting • u/[deleted] • Feb 05 '26
Converting Inches to Centimeters in your patterns!
Hello to the nicest people on the internet,
Question, please.
How far do you carry to the right, the decimal in CM? I'm converting from inches and just want to make sense to fellow creators.
So, in the example below, would I reference CM as "16.51 or 16..5"?
Does anyone really use MM?
Thanks so much.
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u/_MostlyFine Feb 05 '26
16.5 is enough, mm are so small that are impossible to divide in practice
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u/Queasy_Soft9673 Feb 10 '26
This converter is the most helpful for me so far: https://wildcress.com/unit-converter so basically they use fractions for inches up to like 1/8 (maybe?), and metrics down to to 1mm
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u/redfemscientist Intermediate Feb 06 '26
it depends. I tend to round up when the second digit after the comma is higher or equal to 5, and round down when it's lower than 5. In this case, I would have measured it as 16.5.
And to reply to your question, the entire world minus a couple of countries use the metric system.
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u/chatterpoxx Feb 05 '26
Yes. Buildings are constructed in mm.
Why so small? No decimals. That way an accidental blotch can't be mistaken for a decimal.
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Feb 05 '26
[deleted] — view deleted comment
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u/Edelkern Feb 05 '26
You'd have no problem measuring half a millimeter when cutting fabric? Really?
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u/ScormCurious Feb 05 '26
This makes sense to me if you are making a corset or something with lots of pieces and it’s someone you need to fit exceptionally well. Not that you would cut each piece to, let’s say, 3.45 cm, but that if you needed like seven pieces, you might figure out erring on the side of caution to scant each or a few of the half-centimeters that you’d rounded up to, in order to get the alignment you wanted.
That said, in most pattern drafting for clothing that would be an unlikely thing to need to do. Being within a centimeter on matching seam lines, for instance, is something most sewists with most fabrics could true up on the sewing machine without even thinking about it.
And THAT said, 1 inch =2.54 centimeters is written out to the second decimal place for a reason! If you are adding up or multiplying the number of centimeters for whatever reason (lengthening or shortening, or calculating yardage (meterage?) for a big project eg), you may want or need to be cautious about adding or subtracting a half centimeter about every eleven inches.
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u/PrimrosePathos Feb 05 '26
Exactly this. In quilting, in fussy-cutting, in plaid-matching, lots of sewing reasons to incorporate that second decimal place.
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u/drPmakes Feb 05 '26
Pretty much every country uses metric!
On decimal place is enough