About YarnMath

YarnMath is a small set of free calculators for knitters and crocheters, built around one idea: the arithmetic of a project should take a minute, not a scroll through a long article to find a chart.

Each tool does one job. The yarn yardage calculator says how much yarn to buy; the gauge calculator turns a swatch into stitch and row counts and resizes patterns; the hook and needle converters translate US, metric and UK sizes; the yarn weight converter identifies an unlabelled yarn; and the blanket size calculator plans a blanket from a standard size and your gauge. The rules of thumb behind every tool are shown on its page, so you can check the math against your own swatch.

The yardage estimates are calibrated to published patterns and shown with their working. They are estimates for an average tension; the tools add a margin and say so. Size charts follow the Craft Yarn Council's standards where a standard exists.

All calculations run entirely in your browser. Nothing you type is sent to a server or stored by us.

Spotted an error, or want a calculator we don't have yet? We'd genuinely like to know. This site improves through feedback from people mid-project.