Sewing Calculators

Pattern maths, fabric quantities and the adjustments that make a garment fit. 14 calculators.

Seam allowance is the first thing to check when a pattern comes from somewhere unfamiliar, because the convention is not universal and the difference compounds. American home patterns typically use 5/8 inch. European and most industry patterns use 1 cm, which is nearly a quarter inch narrower. Across a bodice with six vertical seams that is over an inch of finished circumference, which is a size. Anyone mixing a Burda pattern with an American technique is fighting that gap without knowing it.

Pattern grading handles the part people get wrong when resizing. Sizes do not scale proportionally: the difference between sizes is distributed unevenly across bust, waist and hip, and armhole depth grows far more slowly than width. Scaling a whole pattern by a percentage on a photocopier gives a garment that is too long in the body and too deep in the armhole.

Ease is treated as its own input rather than folded into the measurements, since the same bust measurement wants very different finished dimensions in a fitted bodice, a shirt, and a coat meant to go over a jumper.