Weaving Weft Calculator

About this calculator

In weaving, the weft is the yarn carried back and forth across the loom, interlacing with the stationary warp threads. The yarn needed depends on picks per inch (PPI, how densely the weft is packed), the fabric's width and length, and a take-up allowance — extra yarn (typically 5–15%) consumed because the weft bends over and under each warp thread instead of lying flat.

Underestimating take-up is a classic beginner mistake that leaves a weaver short of yarn mid-project. Textile engineers, mill planners, and handweavers use this calculation to plan yarn purchases and set loom speeds, since running out partway through a bolt of fabric means a costly dye-lot mismatch on the replacement yarn.