Diamond Carat Calculator
Estimate diamond carat weight from dimensions. Different diamond shapes require different formulas for accurate weight estimation.
How to Use This Calculator
- Select the diamond shape (round, princess, emerald, etc.).
- Enter length in millimeters (for round, this is diameter).
- For fancy shapes, also enter width and height.
- The calculator displays estimated carat weight.
Diamond Carat Weight Formulas
Weight depends on shape and dimensions:
Princess: Carats = L × W × H × 0.0083
Emerald: Carats = L × W × H × 0.0092
Oval: Carats = L × W × H × 0.0062
Marquise: Carats = L × W × H × 0.0059
Pear: Carats = L × W × H × 0.00615
Heart: Carats = L × W × H × 0.0059
Example: 6.5mm round: Carats = 6.5³ × 0.0061 = 1.0 carat. 6.5×6.5×4.0mm princess: Carats = 6.5 × 6.5 × 4.0 × 0.0083 = 1.0 carat. Each shape has a different density factor based on typical cutting proportions. These are estimates—actual weight can vary ±5-10% depending on cut quality.
Full Description
The Diamond Carat Calculator estimates diamond carat weight from dimensions. Different diamond shapes require different formulas because each shape has unique cutting proportions and volumes. Round diamonds use a cubic formula based on diameter, while fancy shapes (princess, emerald, oval, etc.) use formulas based on length, width, and height with shape-specific density factors.
Carat weight is the standard unit for diamond weight (1 carat = 0.2 grams). The calculator uses industry-standard formulas for each shape: Round diamonds use diameter³ × 0.0061, while fancy shapes use length × width × height × shape factor. Each shape has a different density factor based on typical cutting styles. These formulas provide good estimates for well-cut diamonds, but actual weight can vary ±5-10% depending on cut quality, depth percentage, and cutting style.
This calculator helps you estimate diamond carat weight from dimensions. Select shape, enter dimensions, and it calculates estimated carat weight. Use it when buying diamonds, estimating value, understanding diamond sizes, or comparing different shapes. For precise weight, use a diamond scale—this calculator provides estimates based on standard cutting proportions!
Frequently Asked Questions
How is diamond carat weight calculated?
Weight depends on shape and dimensions. Round: carats = diameter³ × 0.0061. Fancy shapes (princess, emerald, etc.): carats = length × width × height × shape factor. Each shape has a different density factor. Example: 6.5mm round = 1.0 carat. 6.5×6.5×4.0mm princess = 1.0 carat.
Why do different shapes have different formulas?
Different diamond shapes have different volumes and cutting styles. Round diamonds are cut to maximize brilliance, while fancy shapes (princess, emerald) have different proportions. Each shape has a unique density factor based on typical cutting styles. The calculator uses industry-standard formulas for each shape.
Is this accurate for all diamonds?
These are estimates based on standard cutting proportions. Actual weight can vary ±5-10% depending on cut quality, depth percentage, and cutting style. For precise weight, use a diamond scale. The calculator provides good estimates for most well-cut diamonds.
What if I only know carat weight?
You can work backwards! For round: diameter = ∛(carats / 0.0061). Example: 1 carat round ≈ 6.5mm diameter. For fancy shapes, dimensions vary more. Use the calculator in reverse: enter estimated dimensions to see if they match your carat weight.