Karat Conversions
Karat Conversion Chart
For Changing 1 Unit Weight
Instructions: Determine starting karat by moving down in Starting Karat column. Move across Desired Karat columns to find multiplier value. Multiply customer's weight by found value. This will be the amount of metal needed to change to the desired karat. If they are lowering the karat - alloy is added. If they are raising the karat - gold is added.
Examples: Customer has 20 dwt. of 18kt gold they want to convert to 14kt. Move down to 18 then across to 14 and the value is .286 x 20 = 5.72 dwt of alloy needed. Customer has 20 dwt of 14kt gold they want to convert to 18kt. Move down to 14 then across to 18 and the value is .667 x 20 = 13.34 dwt of gold needed.
| Starting Karat |
Desired Karat | Gold to Add | ||||||||||||
| 10 | 11 | 12 | 13 | 14 | 15 | 16 | 17 | 18 | 19 | 20 | 21 | 22 | ||
| 8 | 0.143 | 0.231 | 0.333 | 0.455 | 0.600 | 0.778 | 1.000 | 1.286 | 1.667 | 2.200 | 3.000 | 4.333 | 7.000 | |
| 9 | 0.071 | 0.154 | 0.250 | 0.364 | 0.500 | 0.667 | 0.875 | 1.143 | 1.500 | 2.000 | 2.750 | 4.000 | 6.500 | |
| 10 | 0.000 | 0.077 | 0.167 | 0.273 | 0.400 | 0.556 | 0.750 | 1.000 | 1.333 | 1.800 | 2.500 | 3.667 | 6.000 | |
| 11 | 0.100 | 0.000 | 0.083 | 0.182 | 0.300 | 0.444 | 0.625 | 0.857 | 1.167 | 1.600 | 2.250 | 3.333 | 5.500 | |
| 12 | 0.200 | 0.091 | 0.000 | 0.091 | 0.200 | 0.333 | 0.500 | 0.714 | 1.000 | 1.400 | 2.000 | 3.000 | 5.000 | |
| 13 | 0.300 | 0.182 | 0.083 | 0.000 | 0.100 | 0.222 | 0.375 | 0.571 | 0.833 | 1.200 | 1.750 | 2.667 | 4.500 | |
| 14 | 0.400 | 0.273 | 0.167 | 0.077 | 0.000 | 0.111 | 0.250 | 0.429 | 0.667 | 1.000 | 1.500 | 2.333 | 4.000 | |
| 15 | 0.500 | 0.364 | 0.250 | 0.154 | 0.071 | 0.000 | 0.125 | 0.286 | 0.500 | 0.800 | 1.250 | 2.000 | 3.500 | |
| 16 | 0.600 | 0.455 | 0.333 | 0.231 | 0.143 | 0.067 | 0.000 | 0.143 | 0.333 | 0.600 | 1.000 | 1.667 | 3.000 | |
| 17 | 0.700 | 0.545 | 0.417 | 0.308 | 0.214 | 0.133 | 0.063 | 0.000 | 0.167 | 0.400 | 0.750 | 1.333 | 2.500 | |
| 18 | 0.800 | 0.636 | 0.500 | 0.385 | 0.286 | 0.200 | 0.125 | 0.059 | 0.000 | 0.200 | 0.500 | 1.000 | 2.000 | |
| 19 | 0.900 | 0.727 | 0.583 | 0.462 | 0.357 | 0.267 | 0.188 | 0.118 | 0.056 | 0.000 | 0.250 | 0.667 | 1.500 | |
| 20 | 1.000 | 0.818 | 0.667 | 0.538 | 0.429 | 0.333 | 0.250 | 0.176 | 0.111 | 0.053 | 0.000 | 0.333 | 1.000 | |
| 21 | 1.100 | 0.909 | 0.750 | 0.615 | 0.500 | 0.400 | 0.313 | 0.235 | 0.167 | 0.105 | 0.050 | 0.000 | 0.500 | |
| 22 | 1.200 | 1.000 | 0.833 | 0.692 | 0.571 | 0.467 | 0.375 | 0.294 | 0.222 | 0.158 | 0.100 | 0.048 | 0.000 | |
| 23 | 1.300 | 1.091 | 0.917 | 0.769 | 0.643 | 0.533 | 0.438 | 0.353 | 0.278 | 0.211 | 0.150 | 0.095 | 0.045 | |
| 24 | 1.400 | 1.182 | 1.000 | 0.846 | 0.714 | 0.600 | 0.500 | 0.412 | 0.333 | 0.263 | 0.200 | 0.143 | 0.091 | |
| Alloy to Add | ||||||||||||||
Equation for Lowering or Raising the Karat of a Quantity of Gold
A = Weight of alloy needed to change the karat
W = Weight of the gold
K = Karat of the gold present
N = Needed karat
To LOWER the karat, use this formula:
| W (K – N) | = | A | or | (K – N) x W ÷ N = A | ||||
| N | ||||||||
| Example: | ||||||||
| 7 (18 – 14) | = | 7 (4) | = | 28 | = | 2 | or | 18 – 14 x 7 ÷ 14 = 2 |
| 14 | 14 | 14 | ||||||
To RAISE the karat, use this formula:
Amount of the 24K gold needed equals (final karat less beginning karat) times beginning weight divided by (24 less the karat).
| (N – K) x W | = | A |
| (24 – N) |
Example 1: How much 24K gold must be added to 15 grams of 12K gold to raise it to 14K gold?
| Amount of 24K gold needed equals | (14 – 12) x 15 | = 3 grams |
| 24 – 14 |
Example 2: How much gold is required to raise 10 grams of 14K gold to 18K gold?
| Amount of gold needed equals | (18 – 14) x 10 | = 6.6 grams |
| 24 – 18 |