Clay & Shrinkage

Slab Size & Weight Calculator

Calculate the wet cutting dimensions and clay weight for a slab with a target fired size.

Reviewed by ClayCalc Editorial · Updated

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Enter your measurements above and click Calculate.

Wet vs. Fired Dimensions

Because clay shrinks during drying and firing, the wet cutting dimensions must be larger than the desired finished dimensions. This calculator computes exactly how much larger based on your clay body's shrinkage rate.

wet_dimension = fired_dimension × (1 / (1 − shrinkage% / 100))

For example, for a 20cm × 20cm tile in stoneware with 12% total shrinkage:

wet_dimension = 20 × (1 / (1 − 0.12)) = 20 × 1.136 ≈ 22.7 cm

The clay weight calculation uses wet clay density (stoneware: 1.92 g/cm³) multiplied by the calculated wet slab volume.

Method & review note

About this calculation

Uses measured dimensions or weights and a stated arithmetic model. Clay and forming method vary, so production decisions should use test pieces from the actual body and firing.

Reference: Digitalfire — Drying Shrinkage. See the editorial methodology for testing, precision and corrections.

Input handling: Values are sent to the ClayCalc server for this request and are not written to the application database.

Read the Clay Shrinkage Test

Frequently Asked Questions

How thick should slab tiles be? expand_more
Functional floor tiles should be at least 10–12mm thick. Wall tiles can be 6–8mm. Art tiles or decorative pieces can be thinner (4–6mm) but require careful drying with support.
Should I add shrinkage allowance to all dimensions? expand_more
Yes — for precise functional pieces, add shrinkage allowance to all dimensions: length, width, and thickness. The calculator does this automatically based on your clay type.