Diamond Carat Calculator

Our tool uses the following formulas to calculate the total carat weight of the piece of diamond:

• Asscher = Length × Width × Depth × 0.0080 × (1 + GT) × (1 + WC);
• Baguette = Length × Width × Depth × 0.00915 × (1 + GT) × (1 + WC);
• Cushion = Length × Width × Depth × 0.00815 × (1 + GT) × (1 + WC);
• Emerald = Length × Width × Depth × AF × (1 + GT) × (1 + WC);
• Heart = Length × Width × Depth × 0.0059 × (1 + GT) × (1 + WC);
• Oval = Length × Width × Depth × 0.0062 × (1 + GT) × (1 + WC);
• Princess = Length × Width × Depth × 0.0083 × (1 + GT) × (1 + WC);
• Round = Diameter² × Depth × 0.0061 × (1 + GT);
• Trillion = Length × Width × Depth × 0.0057 × (1 + GT) × (1 + WC);
• Marquise: Length × Width × Depth × AF × (1 + GT) × (1 + WC);
• Pear: Length × Width × Depth × AF × (1 + GT) × (1 + WC); and
• Radiant: Length × Width × Depth × AF × (1 + GT) × (1 + WC)

💡 where:

• GT: Girdle thickness factor;
• WC: Weight correction factor; and
• AF: Adjustment factor.

💡 To correctly calculate the total carat weight with the previous formulas, the length, width, depth, and diameter must be input in millimeters. For round diamonds, the depth is around 60% of the diameter.

To know how to calculate the carats of a diamond more accurately, you must consider the following factors:

• GT is the ratio of the girdle thickness to the diamond diameter, usually expressed as a percentage.
  • Because of the difficulty of measuring that tiny thickness, most of the time, GT is estimated visually;
  • It usually lies between 1% (0.01) and 3% (0.03) for round diamonds.
• The weight correction factor accounts for estimation errors caused by non-regular or non-standard shapes.
• The adjustment factor depends on the length-to-width ratio. This diamond carat calculator finds it for you automatically.

Learn more about these three factors in our diamond weight calculator article.

Looking for more about diamonds? Check out collection:

• mm to carat conversion; and
• Carat weight calculator.