What this calculator does
Clay shrinkage works out fired size of a clay piece after drying and firing shrinkage, from its wet (greenware) size. Enter your own figures above and the answer updates as you type: nothing is fixed in the code, so the result reflects exactly the numbers you supply.
The formula this calculator evaluates is printed under the tool and explained below, so you can check the working by hand or reuse it in a spreadsheet.
The formula
FormulaFired dimension = wet dimension × (1 − shrinkage% / 100), applied to each dimension independently
The inputs explained
| Field | What to enter |
|---|---|
| Wet length (cm) | A number, measured in cm. Starts at 20. |
| Wet width (cm) | A number, measured in cm. Starts at 10. |
| Total shrinkage rate (clay body spec, wet-to-fired) (%) | A number, measured in %. Starts at 12. |
Worked examples
Every figure in the tables below is produced by this page’s own calculator at build time, so the numbers and the tool always agree. Select any row to load that scenario.
How the answer changes with wet length
Every other input is held at the calculator’s starting values while wet length varies. Select any row to load that scenario into the calculator.
How the answer changes with wet length
| Wet length (cm) | Fired size | Shrinkage per dimension | Wet size needed for a target fired length |
|---|---|---|---|
| 10 | 8.80 × 8.80 cm | 1.20 × 1.20 cm | 11.36 cm (to fire at 10.00 cm) |
| 15 | 13.20 × 8.80 cm | 1.80 × 1.20 cm | 17.05 cm (to fire at 15.00 cm) |
| 20 | 17.60 × 8.80 cm | 2.40 × 1.20 cm | 22.73 cm (to fire at 20.00 cm) |
| 30 | 26.40 × 8.80 cm | 3.60 × 1.20 cm | 34.09 cm (to fire at 30.00 cm) |
| 40 | 35.20 × 8.80 cm | 4.80 × 1.20 cm | 45.45 cm (to fire at 40.00 cm) |
| 60 | 52.80 × 8.80 cm | 7.20 × 1.20 cm | 68.18 cm (to fire at 60.00 cm) |