Fabric Shrinkage Calculator
Calculate how much extra fabric to buy before pre-washing.
Enter your yardage and shrinkage percentage for cotton, wool, or linen.
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 — 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. Always round up to the nearest quarter yard when purchasing.
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.