Fabric Shrinkage Calculator

Length Shrinkage and Width Shrinkage are measured purely from your Pre-Wash and Post-Wash dimensions -- they describe how the fabric itself behaves, independent of what size you eventually want to cut. Target Finished Length and Width only feed into the separate Required Cut Length and Required Cut Width outputs, which use the already- measured shrinkage rate to work out a cutting size. Changing your target size changes how much fabric you cut, not how much that fabric shrinks.

Area Shrinkage compares the full pre-wash area against the full post-wash area, so it reflects shrinkage happening in both directions simultaneously rather than just one. If a fabric shrinks 5% in length and 5% in width, the surviving area is 0.95 times 0.95, or about 90.25% of the original -- a 9.75% area loss, not 5%. The two linear percentages don't simply add together because the shrinkage compounds across two dimensions at once.

That would produce a negative Length Shrinkage value, which the calculator reports as-is rather than clamping to zero -- a negative percentage means the fabric grew rather than shrank, which does happen with some knits and fabrics that relax after being stretched on the bolt. If you measure growth instead of shrinkage, double-check your measurements before relying on the Required Cut Length figure, since the cutting formula assumes shrinkage rather than expansion.

It divides your Target Finished Length by (1 minus the Length Shrinkage fraction), which is the inverse of the shrinkage calculation itself. For example, at a 4.17% measured shrinkage and a 36-inch target, the calculator recommends cutting about 37.6 inches -- enough extra length that after the fabric shrinks by that same measured rate, the finished piece lands at your target size rather than short of it.