Knit Stretch Calculator

Fold your fabric so the crossgrain (the direction with the most give, usually perpendicular to the selvedge) faces you. Mark a measured section — 4 inches (10 cm) is standard.

Hold one end of your marked section firmly and stretch the other end until the fabric resists comfortably — don't force it to the breaking point, just stretch it to where you'd want it to perform in a garment.

Measure the stretched length.The calculator does the math from there: if 4" stretches to 6", that's 50% stretch.

After stretching, let go and see how well the fabric snaps back to its original length. This is recovery, and it's just as important as stretch. A fabric with great stretch but poor recovery will bag out at the knees, elbows, and seat.

Knit fabrics are grouped into four stretch ranges. Most knit sewing patterns specify which category of stretch their design requires.

• Low stretch (15–25%) — Ponte, double knit, boiled wool. Structured garments like blazers and pencil skirts.
• Moderate stretch (25–50%) — Cotton jersey, interlock, French terry. T-shirts, casual dresses, everyday wear.
• High stretch (50–75%) — Rayon jersey, ITY, spandex blends. Wrap dresses, fitted tops, leggings with some ease.
• Super stretch (75%+) — Swimwear, activewear fabrics, power mesh. Garments with significant negative ease.

More stretch than required is usually fine. If a pattern calls for moderate stretch (25–50%) and your fabric tests at 60%, the garment will simply fit a bit more loosely. You can often size down to compensate.

Less stretch than required is a problem. If the pattern expects 50% and your fabric only gives 30%, the garment will be too tight, restrict movement, and may pop seams. Either choose a different fabric or adjust the pattern widths using the width adjustment factor the calculator provides.

Recovery matters as much as stretch.A fabric that stretches beautifully but doesn't snap back will sag after an hour of wear. When substituting fabrics, match both stretch percentage and recovery quality.

In woven garments, the pattern is always larger than the body (positive ease) to allow movement. Knit garments work differently — because the fabric stretches, the pattern can be smaller than the body. This is called negative ease.

For example, if your hip measurement is 40" and the pattern has 10% negative ease, the pattern piece will measure 36" (40" minus 10%). The fabric stretches the remaining 4" when you put it on, giving a snug, body-skimming fit.

More negative ease means a tighter fit and requires more stretch from the fabric. A T-shirt might use 0–5% negative ease, while leggings may use 15–20% and swimwear up to 30%.

The key rule:your fabric's stretch percentage must be at least as much as the pattern's negative ease percentage. If the pattern has 15% negative ease, your fabric needs at least 15% stretch (and ideally more) to fit comfortably.