Gold Weight Calculator (Karat, Shape & Unit Converter)

Calculate pure gold weight from gross or net weight and karat, deduct stones, see the value at your gold price, or estimate gold weight from dimensions.

Gold Weight Formula

The following formula estimates fine-gold content from stated karat and total gold-alloy mass. The calculator also supports inverse alloy mass and four ideal solid shapes. Shape mass is volume × density; the default binary gold–copper model assumes additive component volumes and can differ from real alloys. Use known density when available.

GW = TW \times K / 24

Where GW is the pure gold weight (ounces or grams)
TW is the total weight of the gold metal piece (ounces or grams)
K is the karat of the gold metal piece

Gold Weight Definition

Gold weight is defined as the actual weight of the pure gold in a piece of gold since most gold is not 100% pure gold and contains other metals and impurities.

How to calculate gold weight?

Example Problem #1:

First, determine the weight of the total gold/metal piece. For this problem, the total piece of gold is measured to be 400 grams.

Next, determine the stated karat. Nominal gold fraction is K/24; the 24K option models 100%. Use Custom percentage for actual assay purity, such as 99.9%.

In this case, the gold is determined to be a 10-karat gold piece.

Finally, calculate the weight of just the gold in the specimen using the formula above:

GW = TW * K / 24

= 400 * 10/24

≈ 166.67 grams of pure gold, rounded to two decimals.

Example Problem #2:

In this next example, the alloy mass is 300 grams and stated purity is 15 karats. Select Custom karat and enter 15.

Using the formula as we did above:

GW = TW * K / 24

= 300 * 15/24

= 187.5

In this case, even though the total weight was less, the gold weight was more because the specimen was of higher purity.