Skip to content

Sett Calculator

Calculate optimal weaving sett (EPI and PPI) from yarn wraps per inch and weave structure. Balanced, warp-faced, and weft-faced sett guide.

Use this result well

Inputs that matter
Wraps Per Inch (WPI), Weave Structure
Output to expect
Sett (EPI) Calculator
  • Check the units and required inputs before comparing results.
  • Keep the assumptions with a copied result so you can reproduce the calculation later.
Was this tool helpful?

Related Tools

Tools you might need next

Warp Calculator

Calculate warp yarn requirements for loom weaving projects. Estimate total warp threads, yardage, and sett from project width and EPI.

Recommended next stepWeaving
Heddle Calculator

Calculate heddles needed per shaft for loom threading. Plan heddle count from warp ends, shafts, and threading pattern for your loom.

Recommended next stepWeaving
Yarn Yardage Calculator

Calculate total yarn yardage for weaving projects including warp and weft. Estimate cones needed from project dimensions and yarn weight.

Recommended next stepWeaving

Reference & details

How it works

Balanced Plain Weave Sett

Balanced plain weave uses half the wraps per inch for both warp and weft. 24 WPI yarn → 12 EPI plain weave sett.

EPI = WPI ÷ 2 (or × 0.5)

Warp-Faced Sett

Warp-faced fabrics (rep, warp satin) pack more warp threads. Higher EPI relative to WPI produces weft-hidden warp-dominant surface.

EPI = WPI × 0.6–0.8

Weft-Faced Sett

Weft-faced fabrics (tapestry, rag rugs) space warp threads widely apart so weft completely covers the warp.

EPI = WPI × 0.3–0.4

Updated: July 2026

Example Scenarios

Balanced plain weave sett: 12 EPI. Twill sett: 15–18 EPI (WPI × 0.6–0.75). Sample before committing to full warp.

Weft-faced rag rug sett: 3–4 EPI. Warp spaced wide for thick weft bundles to cover completely.

Balanced twill at 24 EPI produces lightweight drapey fabric. Plain weave at 20 EPI for gauzy open cloth.

FAQ

Sett is the density of threads — EPI (ends per inch) for warp, PPI (picks per inch) for weft. Correct sett produces fabric with intended hand and appearance.

Wrap yarn snugly (not tight) around a ruler for 1 inch. Count wraps. Average three measurements. Different tension changes WPI slightly.

Twill typically uses 60–75% of WPI (vs 50% for plain weave). Twills pack tighter due to float structure. Always sample with intended weave structure.

No. Each yarn size and fiber has different WPI and optimal sett. Always calculate from the specific yarn's WPI measurement.

Too stiff/open: sett too high, try fewer EPI. Too sleazy/loose: sett too low, increase EPI. Resample with ±1–2 EPI adjustments before full project.

About Sett Calculator

Correct sett determines fabric hand, drape, and structural integrity. Enter yarn wraps per inch (WPI) and desired weave structure to calculate recommended EPI for warp and PPI for weft using standard sett formulas.