About Thimblewise

Thimblewise is a set of free calculators for the arithmetic side of quilting: yardage, cut sizes and layout math.

How it's made

This site is built and maintained with the help of AI, with a person overseeing it. Every formula lives in one shared, automatically tested module, and test cases are checked against published quilting references and charts. Each calculator page shows its formula and a worked example so you can verify the result yourself.

Quilting methods vary, and so do rulers and seam allowances. Treat the results as a careful starting point and double-check before you cut expensive fabric.

Found a mistake or want a calculator?

Email hello@thimblewise.com. Corrections get fixed quickly, and new calculator ideas are very welcome.