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-wheel and connected-pulley measurements before comparing manufacturer-approved settings. Sampling remains necessary because a pulley ratio does not determine finished yarn.

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 reports one measured pulley pair at a time, so you can record and compare compatible settings without assigning a yarn weight from the ratio.

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 provides a rough planning estimate from its displayed project inputs; it does not use weaving sett.

These calculators are built for weavers, spinners, and fiber artists who need accurate technical math without digging through handbooks or spreadsheets. Every self-service calculator listed here is free. Optional professional reviews and project downloads are separate paid offers.