Say what you're throwing and get the wet clay to weigh out — a weight for every piece, plus the batch total. Shrinkage handled, ready to prep.
Type it the way you'd say it. List quantities, sizes and wall thickness — I'll work out the clay.
Clay shrinks as it dries and fires, so a pot thrown at a given size comes out smaller. With this on, I scale the wet clay up to land on the finished size you typed.
The estimator measures the clay surface of each form — walls, base, foot allowance and rim — at an effective wall thickness, converts that to volume, then to weight for moist plastic clay (≈ 1.9 g/cm³). In finished-size mode it first scales every dimension up by the linear shrinkage, so the volume grows by its cube.
Effective wall thicknesses and base allowances are tuned to Lakeside Pottery's dimension-based throwing chart, then cross-checked against The Studio Manager's per-form weights. Tested against 18 reference forms, the model lands within 15% on 16 of them, with a mean error near 6%. Benchmarks at medium walls: a 5×3″ mug ≈ 14 oz, a 7×3.5″ beer mug ≈ 1 lb 6 oz, an 8″ side plate ≈ 2 lb, a 10″ serving bowl ≈ 3 lb 11 oz, a 12×5″ storage jar ≈ 5 lb. The two soft spots — saucers read slightly heavy, very tall narrow pitchers slightly light — both stay inside the ±15% band below.
No calculator knows your exact profile, foot, trimming depth, handle, or clay stiffness, so the number is a starting point, not a rule. The ±15% range reflects that spread. Very tall or very wide pieces can need extra clay for structural support. Weigh, throw, and note your own number for next time.
Default shrinkage is 12%, a common published figure for cone 5–6 stoneware. For accuracy, enter your clay's tested shrinkage from the manufacturer's data sheet (for example Laguna or Standard Ceramic) or from a test tile.