Pottery Clay Shrinkage Calculator
Target Finished Size
Calculate wet size needed for desired finished size
Measure Shrinkage Rate
Calculate your clay's shrinkage from test tile measurements
Formula
Wet Size = Finished Size / (1 - Shrinkage% / 100) | Shrinkage % = (Wet Size - Fired Size) / Wet Size × 100
Frequently Asked Questions
How much does clay shrink when fired?
Total shrinkage (wet to fired) varies by clay body: earthenware shrinks 5-7%, mid-fire stoneware 10-13%, high-fire stoneware 12-15%, and porcelain 12-17%. Shrinkage occurs in two phases: drying (4-6%) and firing (3-12% depending on temperature).
How do I test my clay's shrinkage rate?
Roll out a clay slab and cut a test bar exactly 10cm or 4 inches long. Mark the length clearly. Measure again when bone dry, and again after firing. Calculate: shrinkage % = (original - final) / original x 100. Make multiple test tiles for accuracy.
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