Sett (EPI) Calculator

Enter a measured wraps-per-inch (WPI) to get a starting sett (ends per inch) estimate for plain/balanced weave or twill.

Weave structure

Starting sett estimate

8 EPI

A balanced/plain weave rule-of-thumb estimate (WPI ÷ 2). Lofty knitting yarns often sett closer than this — see the reed/dent reference chart too. Weave a test swatch at this sett before committing a full warp.

Prefer to look up a typical yarn-weight starting point instead? See the yarn weight ↔ reed/dent reference chart.

Frequently asked questions

How do I measure WPI?
Wrap the yarn around a ruler for 1 inch, without stretching or overlapping the strands, and count the wraps. For a fine yarn, wrapping 2 inches and halving the count reduces measurement error.
Where does the WPI ÷ 2 rule come from?
It's a standard starting-point approximation independently confirmed by Handwoven magazine, Liz Gipson/Yarnworker, and Gist Yarn's own weaving guides — roughly half your WPI for a balanced/plain weave, and about two-thirds of WPI for twill (twill floats need a firmer sett to stay closed). It's a planning estimate, not a guarantee for every yarn.
Why does my sett need to be different for twill?
Twill structures float threads over more than one pick at a time, so a looser sett leaves gaps. A firmer sett (about two-thirds of WPI, vs. half for plain weave) keeps the cloth from being too open.
This gave me a different number than the reed/dent reference chart — which is right?
Both can be right for different yarns. WPI ÷ 2 tracks smooth, tightly-spun yarns (cotton, linen, fine wool singles) closely. Lofty, airy knitting yarns compress when you wrap them around a ruler, so a published rigid-heddle chart calibrated on real yarn (like the reed chart) often setts them noticeably closer than WPI ÷ 2 would suggest. For a lofty wool/acrylic knitting yarn, lean on the reed chart over this WPI estimate.
Should I still weave a sample?
Yes — every source this estimate is based on stresses the same point: this is a starting point, not a substitute for a woven test swatch, especially for an unfamiliar yarn.