Casting weight calculator

The casting ratio

The metal piece has the same volume as the model, so its weight is the model weight multiplied by the ratio between the two densities. With wax at 1.0 g/cm³, a 1 g wax model becomes roughly 15.5 g in 18K yellow gold.

Sprues and button

For a full flask, weigh the whole wax tree including its sprues, then add metal for the button that feeds the casting as it cools. A common rule of thumb is about 10 dwt (15.5 g) per flask, or around 10% extra. Use your own workshop's figures where you have them.