Fabric Shrinkage Calculator
Predict how much a garment will shrink by fabric and drying method, or work backward from a target finished size to what you should buy or cut.
Shrinkage estimate
Two directions, one number: shrinkage percent
Every fabric has a rough shrinkage baseline set by its fiber — cellulose fibers like cotton, linen, and rayon give up the most, synthetics like polyester and nylon barely move, and raw, unwashed denim sits at the high end of the scale until its first wash. Heat is the multiplier on top of that baseline: air-drying barely pushes it, a medium tumble cycle pushes it further, and a hot tumble cycle pushes it the most.
That same percentage works in reverse. If you're sewing a garment, buying fabric by the yard, or choosing a size for something you plan to pre-wash, working backward from your target finished measurement tells you how much extra room to build in before the fabric ever meets water.
Frequently Asked Questions
Why does most shrinkage happen on the very first wash?
Fabric fibers get stretched during weaving, knitting, and finishing, and that tension gets locked in until the fibers are relaxed by water and heat. The first hot wash and dry is usually what finally lets the fibers relax back toward their natural, unstretched state, which is why the first wash typically causes most of a garment's lifetime shrinkage — later washes shrink it much less because there's less stored tension left to release.
What does 'pre-shrunk' or 'sanforized' cotton actually mean?
It means the fabric was mechanically shrunk by the mill, under controlled heat and moisture, before it was ever cut and sewn into a garment. Because that relaxation already happened at the factory, a pre-shrunk garment has much less further shrinkage left to give up in your washer — which is exactly why the same cotton can be rated at roughly 3% shrinkage pre-shrunk versus 6% or more for fabric that skipped that step.
Why does heat matter so much more than the wash itself?
Heat is the main driver of fiber relaxation — the wash mostly just gets the fibers wet enough for the heat to act on them. A cool wash paired with air-drying gives fibers comparatively little heat exposure to shrink by, while a hot tumble dryer bathes the same wet fabric in a sustained, high, moving heat that finishes the relaxation far more aggressively. That's why the same garment can shrink noticeably more from an aggressive drying method than from the wash that came before it.
Estimate only. Actual shrinkage varies by weave, weight, and finishing — when it matters, wash a swatch first.