How to determine the correct metal weight

Wax Weight vs. Metal Weight


It is very important to know how to determine the correct metal weight for each wax tree before you cast. Knowing the correct metal weight will ensure that you melt the right amount of metal for your cast. This will make your casting process more cost-effective and more reliable.


To calculate the weight of metal to wax, follow the steps below using the specific gravity for the metal you are using:

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

2. Multiply that total by the specific gravity of the metal you're casting (see table below for metal specific gravity).

3. Example: For a 5-gram wax model, add 0.5 (10% of 5g) to get a total wax weight of 5.5g. For a 14K gold casting, multiply 5.5g x 13.5 specific gravity. The amount of 14K gold needed for this tree is 74.25 grams.


Specific Gravity:

- Brass = 10.0

- Silver = 10.8

- 10K = 12.2

- 14K = 13.5

- 18K = 16.25

- Platinum (95%) = 23.6


How to determine the correct metal weight