Diamond Carat Weight Calculator

Your details

Select the cut style. Each shape uses a different industry coefficient.
Average of minimum and maximum diameter for a round brilliant.
mm
Longest face-up dimension. For ovals and pears this is usually the vertical axis.
mm
Shortest face-up dimension.
mm
Vertical measurement from table to culet (tip of the pavilion).
mm
The girdle adds mass that is not visible face-up. Most gem-quality diamonds are medium to slightly thick.
Optional fine-tuning for unusual proportions or culet size. Leave at 0 for standard diamonds.
%
Estimated weight1 to 2 ct (Popular range)
1.015ct

Approximate carat weight from GIA-standard formula

Weight in milligrams203mg
Weight in grams0.203g
Length-to-width ratio1
Depth percentage60%
1.015 ct
Melee<0.25Small0.25-0.5Medium0.5-1Popular1-2Large2-3Very large3+

Estimated weight: 1.015 carats (203 mg).

  • Round Brilliant diamonds of this weight are approximately 203 mg or 0.2030 g.
  • The depth percentage falls in the ideal range (59-62%) for a round brilliant.
  • This is an estimate. The actual weight can differ by 5-10% depending on exact proportions, culet size and any asymmetry in the stone.

Next stepAt 1 carat or above, a GIA or AGS grading report provides the definitive weight and the 4C assessment that determines market value.

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