Casting weight calculator
Weight of a casting from its shape and size, for grey iron, SG iron, steel, aluminium and brass.
How it is calculated
A casting's weight is its volume times the density of the metal. Work out the volume from the shape, then multiply by the density in grams per cubic centimetre.
Ring: volume = π × (OD² − ID²) ÷ 4 × length
Solid round: volume = π × D² ÷ 4 × length
Block: volume = length × width × height
1 cm³ = 1,000 mm³
Worked example
A grey iron ring 200 mm outside, 120 mm inside and 50 mm high has a volume of 1,005 cm³. At 7.2 g/cm³ it weighs 7.24 kg. At 65% yield the foundry pours about 11.1 kg of metal for each one.
Typical densities used here: grey iron 7.2, SG iron 7.1, cast steel 7.85, aluminium alloys 2.68, brass 8.5, bronze 8.8 and zinc die-casting alloy 6.6 g/cm³.
Questions
How do I calculate the weight of a casting?
Weight in kg = volume in cm³ × density in g/cm³ ÷ 1,000. For a complex part, take the volume from your CAD model.
What is the density of cast iron?
Grey cast iron is about 7.2 g/cm³ and SG (ductile) iron about 7.1 g/cm³. Cast steel is about 7.85 g/cm³.
What is casting yield?
The casting's weight divided by the metal poured, including runners, risers and gates. Many iron foundries work at 55 to 75%.
Should I include machining allowance?
For the rough casting weight, yes. Add the machining allowance to each machined face before you enter the sizes.
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