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Weaving Weft Calculator

Enter your fabric size, picks per inch, and take-up to find the weft yarn length.

How it is calculated

Each pick (one pass of weft) runs the full width of the fabric, and there are ppi × length picks. So weft (in) = ppi × width × length × (1 + take-up ÷ 100), with width and length in inches, ppi in picks per inch and take-up in percent. The result is divided by 36 to get yards: yards = weft ÷ 36, and multiplied by 0.9144 to get metres. The tool also reports the total number of picks, ppi × length. If you leave take-up empty it assumes 10%. Width, length and ppi must be above zero and take-up cannot be negative. It counts only the weft; the warp is a separate calculation.

Worked example

A runner 20 inches wide and 72 inches long woven at 12 picks per inch with 10% take-up. Picks: 12 × 72 = 864. Weft without take-up: 12 × 20 × 72 = 17,280 inches. Add 10%: 17,280 × 1.10 = 19,008 inches. Divide by 36: 528.0 yards, which is 482.8 m (528 × 0.9144). The 864 picks are the total passes of the shuttle or weft carrier.

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Common mistakes

  • Entering width or length in centimetres or feet. The formula expects inches, and ppi is per inch, so other units give a wrong total.
  • Using the finished width instead of the width in the reed. The weft is consumed at the width on the loom, which is wider than the finished cloth; use the loom width if you want a safe figure.
  • Typing take-up as a fraction (0.1) when the field expects a percent (10); that cuts the allowance to almost nothing.
  • Forgetting that ppi is the finished density. Count picks after the cloth is off the loom and relaxed, or the estimate will be off.
  • Buying exactly the calculated amount. The figure has no allowance for sampling, loom waste or a broken pick, so add a margin.

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.

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Comments (1)

  • Editorial team

    Take-up is the number you are least sure of, and it moves the total quickly. For a 20 by 72 inch runner at 12 picks per inch, zero allowance gives 480.0 yards and 10% gives 528.0 yards, a 48-yard difference. Weave a short sample, measure the yarn you pull out, and enter that percentage instead of the default guess. What take-up do you see with your usual yarn and sett?

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