There is a LOT of math involved in knitting, crochet, and sewing and my mom is always asking me for help with her crafting. Her latest request was for help sizing some pleats. The plan was to take a wide piece of cloth and sew it onto a crocheted edging for a dress. Her problem was that she didn’t know how to mathematically determine the size of each pleat. Without some basic understanding of math, she would have been running a rince and repeat / trial and error for days before she found the right pleat size!
So, here’s what we did:
First, measure the width of the piece of fabric you want to pleat and then measure the width you want that fabric to be (in this case, the same size as the crocheted edging).
Full fabric width = 42 in.
Final width = 19 in.
Next determine how many pleats you want (we choose 14) and how much fabric each pleat will take up.
42 in (full fabric width) / 14 (number of pleats we want) = 3 inches.
You can adjust the number of pleats you want to get a reasonable number (the 3 inches) or to adjust for your desired effect.
Now lets run the math to determine the difference between those two numbers and how wide each fold should be.
Subtract 19 from 42 to get 23 (this is how much fabric you need to “pleat” away to “shrink” the 42 inches to the desired 19).
Divide the excess width (23) by 14 (the number of pleats you want) to determine how much fabric to pleat away on each pleat.
23/14 = 1.64
Now we have segmented a 42 inch width into 14 equal area’s of 3 inches with a 1.64 inch fold area! All we have left to do is mark up the cloth, and iron and stitch into place.
For those more math minded folks, here’s a formal equation for pleating: