Weights
Relative Weights
Formula to calculate metal weight and cost from wax models:
- Wax weight (dwt.*) x specific gravity of desired metal** = weight of casting in dwt. x Cost/dwt. + Labor Charges = Cost of Casting.
- Allow some additional weight for the remaining gate.
The top line is the known material (in pennyweights). The first column is the desired material. For example, if you have a wax that weighs .7 dwt, and you want to know its corresponding weight in platinum, go down the wax column to platinum and multiply .7 dwt. (wax weight) by 21.45. 15.02 dwt’s is the corresponding weight in platinum.
|
Wax |
Sterling |
10Y |
14Y |
18Y |
14W |
18W |
Platinum |
| Sterling |
10.36 |
1.00 |
0.90 |
0.79 |
0.67 |
0.82 |
0.71 |
0.49 |
| 10Y |
11.60 |
1.11 |
1.00 |
0.89 |
0.74 |
0.92 |
0.79 |
0.54 |
| 14Y |
13.08 |
1.27 |
1.13 |
1.00 |
0.84 |
1.03 |
0.89 |
0.61 |
| 18Y |
15.60 |
1.49 |
1.34 |
1.19 |
1.00 |
1.23 |
1.06 |
0.73 |
| 14W |
12.65 |
1.22 |
1.09 |
0.97 |
0.81 |
1.00 |
0.86 |
0.59 |
| 18W |
14.65 |
1.41 |
1.26 |
1.12 |
0.94 |
1.16 |
1.00 |
0.68 |
| PT |
21.45 |
2.04 |
1.85 |
1.64 |
1.38 |
1.70 |
1.46 |
1.00 |
*The specific gravity of wax is 1. **See Specific Gravity Chart or Relative Weights.
Weight Conversion
|
| To convert: |
| Pennyweights to grams |
Multiply by |
1.55518 |
| Grams to pennyweights |
Multiply by |
0.64301 |
| Ounces troy to grams |
Multiply by |
31.1035 |
| Grams to ounces troy |
Multiply by |
0.0321507 |
| Ounces avoirdupois to grams |
Multiply by |
28.3495 |
| Grams to ounces avoirdupois |
Multiply by |
0.0352740 |
| Ounces troy to ounces avoirdupois |
Multiply by |
1.09714 |
| Ounces avoirdupois to ounces troy |
Multiply by |
0.911458 |
| Pounds avoirdupois to kilograms |
Multiply by |
0.4535924 |
| Kilograms to pounds avoirdupois |
Multiply by |
2.20462 |
| Kilograms to ounces avoirdupois |
Multiply by |
35.2740 |
| Kilograms to ounces troy |
Multiply by |
32.1507 |
Carat Weight
|
|
Avoirdupois Weight
|
| Used in Weighing Precious and Semi-Precious Stones |
|
Used in Weighing the Base Metals |
| 1 carat |
= 0.20 grams |
|
16 ounces |
= 1 pound |
| 1 gram |
= 5 carats |
|
16 ounces |
= 7000 grains |
| 1 carat |
= 3.086 grains troy |
|
The avoirdupois pound is about 21.5% heavier than the troy pound |
| 1 carat |
= 0.007 ounce avoirdupois |
|
| 1 carat |
= 100 points |
|
28.35 grams |
= 1 ounce avoirdupois |
Troy Weight
|
| Used in Weighing the Precious Metals |
| 24 grains |
1 pennyweight |
| 20 pennyweights (dwt.) |
1 ounce troy |
| 12 ounces |
1 pound troy |
| 5760 grains |
1 pound troy |
| The troy ounce is about 10% heavier than the avoirdupois ounce. |
| 31.1035 grams |
1 ounce troy |
| 1 gram |
15.432 grains troy |
| 1.555 grams |
1 pennyweight (dwt.) |
