FiberMath is a small, independent site of free calculators for knitters, crocheters and quilters. It answers the question every maker asks before starting a project: how much yarn or fabric do I need to buy?
Why we built it
Most yarn and fabric estimates online are rules of thumb repeated from site to site. We wanted numbers you can trust, so we built them from real data and show the assumptions behind every result.
Where our numbers come from
- Yarn for blankets: median yardage per square inch from 2,681 knitted and crocheted blanket patterns published on Ravelry, grouped by craft and yarn weight, with the typical range shown next to each estimate.
- Sizes: standard US blanket and bed dimensions.
- Quilting: the usable fabric widths, seam allowances and margins that quilt shops and longarm quilters work with.
Our calculators
- How much yarn for a blanket
- Quilt backing calculator
- Quilt binding calculator
- Quilt batting calculator
Every calculator works in inches and yards or in centimetres and metres, runs in your browser and needs no sign-up.
Get in touch
Found a number that does not match your experience, or want a calculator we do not have yet? Write to [email protected]. We read every message.