Throwing Dimensions Calculator
Work out the diameter and height a lump of clay can make, and the clay needed for a shape you have in mind.
At a glance
- What you enter
- What are you working out?, Clay weight, Target fired diameter, Height divided by diameter, Wall thickness, Wet clay density, Centring and throwing loss, Linear shrinkage
- What you get
- Wet diameter to throw, Wet height to throw, Fired diameter, Fired height, Clay to weigh out, Capacity, Capacity, Fired interior diameter, Fired interior height, Wall thickness as a share of the diameter
- Formula shown
- Yes, every step, right below your results.
- Cost and privacy
- Free, no account needed, and nothing you type is stored.
See worked examples ↓ Read the FAQ ↓ Share this calculator ↓
Results are estimates for general information only, always verify with a professional or official source before acting on them.
How to use the Throwing Dimensions Calculator
- 1 Enter What are you working out?
- 2 Enter Clay weight (g), The lump on the wheel head, including the loss.
- 3 Enter Target fired diameter (cm), Only used in the second mode, for a piece sized to a finished dimension.
- 4 Enter Height divided by diameter, About 1 for a bowl or a low jar, 1.5 to 2 for a mug or a cylinder, above 2.5 for a tall narrow form.
- 5 Enter Wall thickness (mm), Six to ten millimetres for domestic ware. Measure a pot you have made and like.
- 6 Enter Wet clay density (g per cubic cm), Stoneware is about 1.8 to 2.0 as wet clay.
- 7 Enter Centring and throwing loss (%), Ten to fifteen percent is normal, more for a tall form or a new shape.
- 8 Enter Linear shrinkage (%), Five to twelve percent from wet to fired.
- 9 Press Calculate. You get Wet diameter to throw, Wet height to throw, Fired diameter, Fired height, Clay to weigh out, Capacity, Capacity, Fired interior diameter, Fired interior height, Wall thickness as a share of the diameter, and every intermediate step stays visible under "How is this calculated?"
- 10 Change one number at a time to see what moves the result, that is usually the most useful thing a calculator can tell you.
Worked examples
Real numbers run through this calculator. Open any example to load it into the form above and change it.
1.2 kilograms into a cylinder
A 1.0 height to diameter ratio with an 8 mm wall and a 12 percent loss.
You enter
- What are you working out?
- 1
- Clay weight
- 1,200 g
- Target fired diameter
- 18 cm
- Height divided by diameter
- 1
- Wall thickness
- 8 mm
- Wet clay density
- 1.95 g per cubic cm
- Centring and throwing loss
- 12%
- Linear shrinkage
- 7%
You get
- Wet diameter to throw
- 14.73 cm
- Wet height to throw
- 14.73 cm
- Fired diameter
- 13.70 cm
- Fired height
- 13.70 cm
- Clay to weigh out
- 1,200.00 g
- Capacity
- 1.48 L
- Capacity
- 50.14 fl oz
- Fired interior diameter
- 12.10 cm
- Fired interior height
- 12.90 cm
- Wall thickness as a share of the diameter
- 5.8%
615 cubic centimetres of clay and 542 of working wall, which makes a wet pot about 14.7 centimetres across and the same tall, firing to about 13.7 with a capacity of about 1.5 litres.
A tall mug shape
The same clay at a height to diameter ratio of 1.8.
You enter
- What are you working out?
- 1
- Clay weight
- 1,200 g
- Target fired diameter
- 18 cm
- Height divided by diameter
- 1.80
- Wall thickness
- 8 mm
- Wet clay density
- 1.95 g per cubic cm
- Centring and throwing loss
- 14%
- Linear shrinkage
- 7%
You get
- Wet diameter to throw
- 15.20 cm
- Wet height to throw
- 27.36 cm
- Fired diameter
- 14.13 cm
- Fired height
- 25.44 cm
- Clay to weigh out
- 1,200.00 g
- Capacity
- 3.04 L
- Capacity
- 102.80 fl oz
- Fired interior diameter
- 12.53 cm
- Fired interior height
- 24.64 cm
- Wall thickness as a share of the diameter
- 5.7%
The same lump goes taller and narrower: about 6.4 centimetres across and 11.6 tall wet, firing to 6 by 10.8 with a capacity near 0.25 litres. The same clay makes a very different pot.
Working back from a 18 cm target
A 1.2 height to diameter bowl sized to a finished dimension.
You enter
- What are you working out?
- 2
- Clay weight
- 1,200 g
- Target fired diameter
- 18 cm
- Height divided by diameter
- 1.20
- Wall thickness
- 8 mm
- Wet clay density
- 1.95 g per cubic cm
- Centring and throwing loss
- 12%
- Linear shrinkage
- 7%
You get
- Wet diameter to throw
- 19.35 cm
- Wet height to throw
- 23.23 cm
- Fired diameter
- 18.00 cm
- Fired height
- 21.60 cm
- Clay to weigh out
- 2,979.25 g
- Capacity
- 4.39 L
- Capacity
- 148.57 fl oz
- Fired interior diameter
- 16.40 cm
- Fired interior height
- 20.80 cm
- Wall thickness as a share of the diameter
- 4.4%
A fired 18 cm needs a wet 19.35 cm and about 2.6 kilograms of clay to weigh out, more than twice the 1.2 kilograms in the first example.
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