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Essential math for sewing

There are a few math equations that will really boost your successes in sewing. The first is finding the circumference of a circle. Why do I need to know how to find the circumference of a circle, you may ask? Well, if you ever need to know how much trim to buy for the hem of a circle skirt, or table cloth, you will need this equation. [read on!]

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Comment by Cathy on August 12, 2009 at 9:20am: Another bit of information that is handy to have is how to figure the diagonal of a square - for some reason I have been asked this several times lately - Multiply one side of your square by
1.444- this will give you your diagonal measurement. - I am better in geometry now than
I was when I was in school.

Comment by Katriina Alanko on July 23, 2009 at 7:42pm: I find that my high school geometry come in very handy. I've had all sorts of occasions to use the Pythagorean Theorem and all the other formulae for finding the surface area of circles, rectangles, and triangles. In a lot of cases, they make for interesting shapes to wear, without having to dig out a commercial pattern.

Comment by Ags on July 23, 2009 at 2:15pm: I needed to use this equation just recently when making a basket liner for someone's circular hamper. Here is some other information has been very useful to me. I wrote it down and keep it in the front of my customer notebook and in the open where I can see it all the time. This is for converting decimal fractions to inches - common fractions used in sewing.

.0625 = 1/16
.125 = 1/8
.1875 = 3/16
.25 = 1/4
.3125 = 5/16
.375 = 3/8
.5 = 1/2
.5625 = 9/16
.625 = 5/8
.6875 = 11/16
.75 = 3/4
.8125 = 13/16
.875 - 7/8
.9375 = 15/16

Use the closest decimal fraction to the one you need, always rounding up.