Clay Shrinkage Calculator

Clay never finishes the size it started at. As a piece dries and then fires, it shrinks — typically somewhere between 6% and 15%, depending on the clay body — so the mug you throw today will be noticeably smaller once it's out of the kiln.

That's easy to forget mid-project, and hard to judge accurately by eye, especially for anything that needs to fit something else afterward: lids, stacking sets, a piece sized for someone's hands, or work meant to match something you've already made.

Use the calculator below either way round — tell it the finished size you're aiming for and it'll tell you what to make now, or tell it the size you're making now and it'll tell you roughly where it'll land after firing.

A note on accuracy: shrinkage isn't identical across all clay. Earthenware, stoneware, and porcelain all behave differently, and even within one clay body it shifts slightly depending on your batch, how dry the piece gets before firing, and your firing temperature. The presets here are solid starting estimates, but if precision really matters — sets, lids, anything with a tight tolerance — it's worth throwing a small marked test tile in your own clay, firing it once, and measuring your exact rate before committing a full piece to size.

Once you've got your numbers, our stamps, texture rollers, and cutters are ready whenever you are.

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