Clay & Shrinkage

Slab Size & Weight Calculator

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

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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.

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.