About Fabric and Yarn Math

Fabric and Yarn Math does the sums that come before the first cut or the first stitch: how much fabric to buy for a set of pieces, how many skeins a blanket takes, how many stitches to cast on at your gauge, and how big a blanket for each bed size should be.

Every calculator shows its method on the same page. Most answers come straight from your own measurements and swatch; where a figure comes from elsewhere, such as standard blanket sizes, the page names the source.

How the calculators are checked

Each calculator's formulas are covered by automated tests that include worked examples and an independent cross-check implementation, and the method is explained on every tool page. If you find a wrong answer, please tell us.