Fabric Shrinkage Calculator
Measure how much a fabric shrinks from a test wash, or turn a known shrinkage into the length you need to cut so the finished piece lands at exactly the right size.
Measured shrinkage
Two questions, one relationship
Shrinkage is just the fractional change between a before and an after length. Measured forwards, it turns a washed swatch into a percentage you can put on a spec sheet. Run backwards, that same percentage tells you how much extra to cut so a piece finishes at the size you want after its first wash. Both come from one simple ratio, which is why the tool offers each direction.
Testing on a marked swatch before committing a whole cut is the cheapest insurance in the workroom. Fabrics can also grow rather than shrink, and can move differently along the length and the width, so record what you measure and cut accordingly.
Frequently Asked Questions
How do you calculate fabric shrinkage percentage?
Measure a marked length before washing and again after drying, then use shrinkage % = (before − after) ÷ before × 100. A swatch marked at 100 cm that comes back at 95 cm has shrunk 5%. A negative result means the fabric relaxed or grew rather than shrank.
How much extra fabric should I cut to allow for shrinkage?
To end up at a target finished length after a known shrinkage, cut = finished ÷ (1 − shrinkage%/100). For a 90 cm finished piece from a fabric that shrinks 10%, cut 90 ÷ 0.90 = 100 cm. The tool's pre-cut mode does this for you.
Why pre-wash fabric before cutting?
Most residual shrinkage happens in the first wash. Pre-washing (or 'scouring') the fabric before you cut means the garment or item is already at its stable size, so seams don't pucker and pieces don't end up short after the customer's first laundering.
Does shrinkage differ between length and width?
Yes. Woven and knitted fabrics often shrink more in one direction than the other — commonly more in the lengthwise (warp) direction for wovens. Test and record both directions separately if fit is critical, running the tool once for each.
What causes fabric to shrink?
Mainly relaxation of tension locked in during weaving, knitting, and finishing, plus fibre swelling from water and heat. Natural fibres like cotton, wool, and linen shrink more than most synthetics. Heat in washing and tumble-drying accelerates it, which is why care labels limit temperatures.
Educational estimate only. Real shrinkage varies with fibre, construction, wash temperature, and drying method, and can differ between length and width — always test your actual fabric and wash cycle.