Clay test log.

Keep each clay body’s measurements and firing conditions together. Compare drying, firing and total linear shrinkage, then use a completed test in the calculator.

Saved tests stay only in this browser on withcalculator.com. Entries saved on clay.withcalculator.com do not transfer automatically; your old staging log remains separate.

Prefer paper? Print a clay shrinkage test card for measurements, firing conditions and studio notes. Entries on the card are not saved.

Private to this browser

Records are stored only in this browser profile’s local storage. They are not uploaded, synced, included in URLs, or sent with analytics. Clearing browser data or switching profiles/devices can remove or hide them. Export a CSV backup if you need one elsewhere. Storage errors switch this page to temporary in-memory records; those disappear when you leave or reload. Corrupt saved data is never overwritten automatically.

Add a test

Clay body (required)

Test label (required)

Test date (required)

Measurement unitChanging units converts entered lengths.

Wet length (required)

Bone-dry length (optional; leave blank while drying)

Final-fired length (optional; leave blank while in progress)

Firing cone / temperature

Schedule and atmosphere notes

Drying % = (wet − dry) ÷ wet × 100. Dry-to-fired % = (dry − fired) ÷ dry × 100. Total wet-to-fired % = (wet − fired) ÷ wet × 100. Each rate uses its own starting length; do not add stage percentages. Equal lengths mean 0% shrinkage. Expansion is not supported.

Mark two points on a small test bar. Measure the same marks when wet, bone-dry, and after the final firing once cooled; use the same body, forming method, and firing process for meaningful comparisons. Results vary with clay and process; keep tests separate rather than averaging different conditions. See Digitalfire’s shrinkage test.

Your tests

No tests recorded yet. Add your first test above. No sample records are preloaded.