Fabric Shrinkage Calculator

Why Fabric Shrinks

Most natural and semi-natural fabrics shrink when first washed because the fibers absorb water and swell. During the weaving or knitting process, threads are held under tension. When the fabric is washed for the first time, that tension releases and the cloth contracts. This is why pre-washing fabric before cutting your pattern is one of the most important steps in garment construction.

Typical Shrinkage Rates by Fiber

Cotton shrinks approximately 3–5% in a standard warm-water wash. Linen tends to shrink 3–5% as well, though high-quality linen may shrink up to 10% the first time. Wool is the most unpredictable. Untreated wool can shrink 5–10% or more in warm water, while superwash wool is treated to resist shrinkage. Silk typically shrinks 2–4% in gentle washing. Polyester and other synthetics generally shrink less than 1–2%, though they can lose shape under high heat. Blended fabrics behave somewhere between their component fibers.

Pre-Washing Best Practices

Always pre-wash fabric in the same conditions you plan to launder the finished garment. If you will machine wash in warm water, pre-wash in warm water. If dry clean only, take the fabric to the cleaner before cutting. Wash selvedge edges first to prevent unraveling. Press the fabric flat with an iron before measuring, because heat can cause further slight shrinkage.

The Formula

To find how much fabric to buy, divide your needed yardage by (1 − shrinkage rate). For example, if you need 3 yards and expect 5% shrinkage: Extra fabric = 3 ÷ (1 − 0.05) = 3 ÷ 0.95 = 3.16 yards. Cutting counters work in eighths of a yard, so round up to the next eighth: 3 1/4 yards.

Do not subtract the shrinkage instead of dividing by it. Taking 5% off 3 yards gives 2.85, which is the wrong direction, and 3 × 1.05 = 3.15 is close but drifts as the percentage climbs. At 15% the correct answer is 3.53 yards and the multiply-by shortcut says 3.45, which is nearly 3 inches short.

Shrinkage Happens In Both Directions

Buying extra length covers you along the bolt, and that is usually the bigger movement, but woven fabric contracts across the width too. A 44-inch cotton typically comes back from a hot wash at 42 to 43 inches. Knits are worse and shrink most in length. If your pattern layout is tight to the selvedge, measure the fabric again after pre-washing rather than trusting the bolt label.

Multiple Washes

Most shrinkage happens in the first wash. A second wash causes minimal additional change, usually less than 1%. Once pre-washed, your fabric should be dimensionally stable for the life of the garment.