Free knitting & crochet tools

Yarn math, done for you

How much yarn to buy, how many stitches to cast on, which hook the pattern means, and what size to make it. Six calculators, no sign-up, nothing to install.

• Yarn Yardage Calculator

  How much yarn a blanket, scarf or wrap needs from its size, yarn weight and stitch, and how many skeins to buy.

• Gauge Calculator

  Turn your swatch into cast-on stitches and rows, or resize a pattern written for a different gauge.

• Crochet Hook Size Converter

  US letters, millimetres and UK numbers, converted both ways with the full chart.

• Knitting Needle Size Converter

  US, metric and old UK needle sizes, and the nearest standard size for any millimetre.

• Yarn Weight Converter

  Identify a mystery yarn from wraps per inch, gauge or tool size, and see its UK/Australian ply name.

• Blanket Size Calculator

  Standard blanket sizes, with the cast-on, row count and yardage for yours at your gauge.

Why the math matters

Yarn is bought before the project starts and rarely available in the same dye lot afterwards, so an estimate that's a skein short costs a real mismatch. Gauge decides whether a sweater fits or a blanket ends up a foot narrower than the photo. And every pattern assumes you can read its hook size, in whichever of three systems it was written. These tools exist so you can settle each of those questions in a minute and get back to the needles.

Every number here is shown with its working, so you can check it against your own swatch. Yardage figures are estimates for an average tension; the calculator adds a margin and says so. Nothing you type leaves your browser.