Definition
Stretch percentage is how much a knit fabric lengthens when stretched, relative to its relaxed length: 10 cm that stretch to 15 cm is 50% stretch.
Knit patterns often state the stretch they were drafted for, such as "for knits with at least 40% stretch", because a garment designed for a stretchy fabric comes out too tight in a stable one.
How to measure it:
- Fold the fabric along the crosswise grain, a few centimeters from a cut edge.
- Mark 10 cm (4 in) along the fold.
- Hold one mark still and stretch gently until the fabric resists, without distorting it.
- Measure the new length. Stretched to 15 cm (6 in), the fabric has 50% stretch; to 12.5 cm (5 in), 25%.
Then let go and check the recovery: a good knit returns to 10 cm at once. One that stays longer will bag at the knees and elbows.
| Stretch | Category | Examples |
|---|---|---|
| Under 25% | Stable | Ponte, scuba, some French terry |
| 25–50% | Moderate | Cotton jersey, interlock |
| 50–75% | Stretchy | Jersey with elastane, rib |
| Over 75% | Very stretchy | Swimwear and activewear fabrics |
Measure lengthwise too: two-way stretch fabrics stretch mainly across, four-way fabrics in both directions, which leggings and swimwear need.
Stretch decides how much negative ease a garment can have and how short to cut bands of rib knit. See knit fabric for more.