How To Determine Metal Weight for Wax Trees

Knowing how to determine metal weight for each wax tree ensures that you have the right amount of metal for your cast.

Last edited: 10/7/2019

Knowing how to determine the correct metal weight for each wax tree before you cast ensures that you melt the right amount of metal for your job, making your casting process more cost-effective and more reliable.

Specific Gravities:
24KY = 19.32

18KY = 15.58

14KY = 13.07

10KY = 11.57

Fine silver = 10.49

Sterling = 10.36

Platinum = 21.54

Caster's brass chunks = 8.4

Caster's white bronze chunks = 8.1

Ancient bronze = 8.8

Yellow bronze = 8.4

Manganese bronze = 8.3

Nickel silver = 8.8

Alpaca = 8.6


First, weigh your wax models along with main and gate sprues. Then add an additional 10% to account for your button.

Multiply that total by the specific gravity of the metal you're casting (see table above for a general guideline).


Example: For a 5-gram wax model, add 0.5 (10% of 5g) to get a total wax weight of 5.5g. For a 14KY gold casting, multiply 5.5g x 13.07 s.g. The amount of 14KY gold needed for this tree is 71.89 grams.