Woven fabric is built from two sets of yarn crossing at right angles: warp and weft. Knowing the difference helps you order the right yarn for each.
Warp: the lengthwise yarns
The warp runs the length of the fabric and is held under tension on the loom. Because it takes the strain of weaving, warp yarn needs higher strength and twist — and is often sized (coated) to survive. Strength metrics like CSP matter most here.
Weft: the crosswise yarns
The weft (also called filling or pick) is woven across the warp. It carries less stress, so weft yarn can be softer or more economical — open-end yarn is common for weft.
Why it affects your order
A construction like 40 × 40 / 132 × 72 gives warp count × weft count / EPI × PPI. You may specify different yarn for warp and weft — a stronger ring-spun warp and an economical weft. See weaving yarn and read a full fabric spec sheet.
We supply warp and weft yarn matched to your construction.
See the glossary for warp, weft, EPI and PPI.