Work out fabric shrinkage instantly with clear inputs, formula shown and shareable results.
Shrinkage is the lost length over the original, and the purchase length divides the finished requirement by one minus that fraction rather than multiplying by one plus it. Dividing rather than multiplying matters: at 6% shrinkage you need 6.4% more fabric, and the gap widens fast with heavier shrinkage.
Shrinkage
shrinkage = (before - after) / before
Length to buy
buy = finished length / (1 - shrinkage)
shrinkage = (before - after) / before. Shrinkage is the lost length over the original, and the purchase length divides the finished requirement by one minus that fraction rather than multiplying by one plus it.
Dividing rather than multiplying matters: at 6% shrinkage you need 6.4% more fabric, and the gap widens fast with heavier shrinkage.
Enter length before washing, length after washing, finished length you need. The defaults shown are a realistic worked example — swap in your own figures to get a result you can use.