Karat Conversions

By Stuller | June 5, 2013

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