Free Weaving & Spinning Calculators

Weaving and spinning involve some of the most calculation-heavy math in fiber arts. Before a weaver throws the first shuttle, they need to know the correct ends per inch (EPI) for their yarn and intended sett, how many yards to wind onto the warp beam, and how much loom waste to factor in. Before a handspinner winds off the bobbin, they need to confirm their drive ratio and whorl size are producing the twist-per-inch their target yarn weight requires. Get this math wrong and you waste fiber, warp thread, and hours of setup time.

FiberTools weaving and spinning calculators are built on the technical specifications used by the handweaving and handspinning communities. The sett calculator uses the standard formula — sett equals WPI divided by 2 for plain weave, divided by 1.5 for twill — to generate a recommended EPI from your actual yarn rather than a generic chart value. The WPI calculator walks you through the wrapping procedure to measure your yarn’s true weight category, which is the necessary first step before any other weaving calculation. The spinning ratio calculator handles multi-whorl wheel setups so you can compare drive combinations on paper before committing at the wheel.

The thread converter bridges the gap between commercial weaving thread systems: denier, tex, and yards-per-pound all appear on thread labels from different manufacturers with no direct comparison, and this tool converts between all three in both directions. For finished yarn, the standard yarn calculator estimates yardage requirements from sett and project dimensions.

These calculators are built for weavers, spinners, and fiber artists who need accurate technical math without digging through handbooks or spreadsheets. All tools are free, work on any device, and require no account or login.