Calculate an alloy’s total weight, metal A weight, or percentage from two known values in grams, kilograms, pounds, or ounces instantly.
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Alloy Percent Formula
The alloy percent calculator uses the relationship between the total alloy weight, the weight of one metal in the alloy, and that metal’s percentage by weight.
- P = percentage of Metal A in the alloy, as a percent
- W_A = weight of Metal A
- W_T = total weight of the alloy
To calculate the weight of Metal A when the total weight and percentage are known, the formula is rearranged:
To calculate the total alloy weight when the weight of Metal A and its percentage are known, the formula is rearranged again:
- Calculating percentage: enter total weight and weight of Metal A. The calculator divides Metal A’s weight by the total alloy weight, then multiplies by 100.
- Calculating Metal A weight: enter total weight and percentage. The calculator converts the percent to a decimal and multiplies by total weight.
- Calculating total weight: enter Metal A weight and percentage. The calculator divides the Metal A weight by its percent share.
- Unit handling: weights can be entered in grams, kilograms, pounds, or ounces. The calculation converts weights to grams internally, then converts the result back to the selected output unit.
Common Alloy Percentage Benchmarks
These common alloy compositions can help you check whether a result looks reasonable. Actual specifications can vary by grade or standard.
| Alloy or material | Example metal percentage | Meaning |
|---|---|---|
| Sterling silver | 92.5% silver | 92.5 parts silver per 100 parts total alloy |
| 18 karat gold | 75% gold | 75 parts gold per 100 parts total alloy |
| 14 karat gold | 58.3% gold | About 58.3 parts gold per 100 parts total alloy |
| Cartridge brass | About 70% copper | Often about 70 parts copper and 30 parts zinc |
Weight Unit Conversions Used
| Unit | Equivalent in grams |
|---|---|
| 1 gram | 1 g |
| 1 kilogram | 1000 g |
| 1 pound | 453.592 g |
| 1 ounce | 28.3495 g |
Example Calculations
Example 1: Find the percentage of copper in an alloy
You have a 500 g alloy sample that contains 350 g of copper.
The alloy is 70% copper by weight.
Example 2: Find the weight of silver in sterling silver
You have 2 kg of sterling silver that is 92.5% silver.
The alloy contains 1.85 kg of silver.
FAQ
Is alloy percentage calculated by weight or volume?
This calculator uses percentage by weight. For alloys, weight percent is common because different metals have different densities. A 50% weight mixture is not always the same as a 50% volume mixture.
Can the percentage be greater than 100?
No. For a single metal within an alloy, the percentage should normally be between 0% and 100%. A result above 100% usually means the metal weight entered is larger than the total alloy weight, or the units were selected incorrectly.
Do all metal percentages in an alloy have to add to 100%?
Yes, if you list every component in the alloy by weight percent, the percentages should add to 100%. Small differences can occur because of rounding, impurities, or measurement precision.