Diamond Carat to mm Calculator Formula
Understand the math behind the diamond carat to mm calculator. Each variable explained with a worked example.
Formulas Used
Approximate Diameter
diameter_mm = 6.5 * pow(carats, 1 / 3)Weight in Milligrams
weight_mg = carats * 200Weight in Grams
weight_grams = carats * 0.2Variables
| Variable | Description | Default |
|---|---|---|
carats | Diamond Weight(carats) | 1 |
How It Works
Diamond Carat to Millimeter Conversion
Diamond size (diameter) relates to carat weight through the cube root, since volume increases with the cube of the diameter.
Formula (Round Brilliant)
Diameter (mm) = 6.5 x Carat^(1/3)
One carat equals 200 milligrams (0.2 grams). A 1-carat round diamond is approximately 6.5 mm in diameter. Doubling the carat weight only increases diameter by about 26% (cube root of 2).
Worked Example
A 1.0 carat round brilliant diamond.
carats = 1
- 01Diameter = 6.5 x 1.0^(1/3) = 6.5 x 1.0 = 6.5 mm
- 02Weight = 1.0 x 200 = 200 mg
- 03Weight = 1.0 x 0.2 = 0.2 grams
Ready to run the numbers?
Open Diamond Carat to mm Calculator