Carat to Grams Converter

One metric carat is exactly 0.2 grams, or 200 milligrams. This is the international standard used for gemstones since 1907. So a 5 carat stone weighs exactly 1 gram.

For gemstones, a carat is a unit of mass (0.2 g), not size. Two diamonds of the same carat weight can look different in size depending on their cut and density. Do not confuse the gemstone carat with the gold karat, which measures purity, not weight.

Multiply the carat value by 0.2: grams = carats x 0.2. To convert grams to carats, divide by 0.2 (or multiply by 5): carats = grams x 5. This converter also shows the weight in milligrams and ounces.

A point is one hundredth of a carat, so 100 points equal 1 carat. A 0.25 carat diamond is often called a 25 point stone. In grams, one point is 0.002 g (2 mg).