Pottery Clay Weight Calculator
The pottery clay weight calculator estimates how much wet clay you need to throw or build a ceramic piece. By modelling your piece as a hollow cylinder (suitable for mugs, bowls, vases, and cylinders), the calculator finds the wall volume from the outer diameter, height, and wall thickness, then multiplies by wet clay density to give the clay weight in grams and pounds. A waste and trimming allowance is added to give you the total weight to weigh out before starting. This is particularly useful for potters who want to weigh consistent batches of clay for sets of mugs or plates.
Clay weight formula
Inner radius = Outer diameter / 2 - Wall thickness
Outer radius = Outer diameter / 2
Wall volume (cm3) = pi x (Outer radius^2 - Inner radius^2) x Height
Clay weight (g) = Volume x Density (g/cm3)
With waste = Clay weight x (1 + Waste % / 100)
Frequently asked questions
How much does clay shrink when fired?
Most pottery clays shrink 10 to 15% in linear dimensions from wet to fired (bisque and glaze fire combined). This means a piece that is 10 cm tall when thrown will be approximately 8.5 to 9 cm tall after firing. The total volume shrinkage is roughly 25 to 40%.
What is the density of wet pottery clay?
Wet throwing clay has a density of approximately 1.75 to 1.85 g/cm3 (grams per cubic centimetre). Bone dry clay is lighter at about 1.5 g/cm3, and fired stoneware is approximately 2.0 to 2.4 g/cm3 depending on the clay body and firing temperature.
How do I calculate the volume of a cylinder for a mug or vase?
For a hollow cylinder: Volume = pi x ((outer radius)^2 - (inner radius)^2) x height. The inner radius equals outer radius minus wall thickness. This calculator performs that calculation automatically once you enter the outer diameter, height, and wall thickness.
How much extra clay should I allow for trimming and waste?
When throwing on the wheel, allow 15 to 25% extra for the clay left on the wheel head (the foot), waste from centring, and trimming. Hand-builders may need 10 to 15% extra. Add this using the waste factor input.
Can I use this calculator for handbuilding as well as wheel throwing?
Yes. The clay volume and weight calculations apply equally to wheel-thrown and handbuilt forms. For handbuilt slabs, the shape calculation may differ, but once you know your slab dimensions (length x width x thickness), the volume and weight formula is the same.
Sources
- National Council on Education for the Ceramic Arts (NCECA): NCECA - Ceramic Arts Education.
- Smithsonian Institution: Ceramics Research Resources.
Reviewed by the CalculatorHub team, edited by James Graham, 14 June 2026. See our methodology.