Independent buying guides for pottery

Clay Shrinkage Calculator

Clay shrinks as it dries and fires. Enter your clay's total shrinkage and either the size you will make or the finished size you need.

Result

Make it this size wet
4.55
Volume lost in firing
about 32%

Shrinkage is printed on the clay bag or data sheet. Test your own clay with a marked tile, since it varies with firing temperature.

How this calculator works

Shrinkage is a percentage of the wet size. Fired size = wet size x (1 - shrinkage). To hit a target, wet size = target / (1 - shrinkage). Volume shrinks even more, roughly with the cube of the linear change.