mm to Ct weight conversion Table

Factors that Influence diamond size and carat weight

The conversion from millimetres (mm) to carats (ct) in diamonds is influenced by several factors, primarily because carat measures weight while millimetres measure size. Here are the key factors that impact this conversion:

Shape

Different shapes distribute a diamond’s carat weight in various ways. Shapes such as marquise, pear, or oval might appear larger than a round diamond of the same carat weight because their elongated shapes cover more surface area.

Cut

The cut of a diamond significantly affects its proportion, which in turn influences how large the diamond appears relative to its weight. For example, a shallow-cut diamond might have a larger diameter (measured in mm) but a lower carat weight because it doesn’t have much depth. Conversely, a deep-cut diamond might appear smaller for its weight.

Depth and Table Size

The depth (height of a diamond from the culet to the table) and the size of the table (the top surface of the diamond) affect how the carat weight is distributed vertically and horizontally. Diamonds with a larger depth or smaller table may weigh more without a corresponding increase in horizontal size.

Girdle Thickness

The girdle is the widest edge of a diamond where the top (crown) meets the bottom (pavilion). A thick girdle adds weight to the diamond without necessarily increasing its visible size.

Density

Although not widely variable in diamonds, slight differences in density (how tightly the carbon atoms are packed) can affect the weight without changing the size.

Convert Diamond mm Size to Diamond Carat Weight

This conversion chart will help you estimate the carat weight of a diamond based on its millimetre (mm) measurements. It’s important to note that this conversion is based on diamonds that are ideally cut. Because the cut can affect the diamond’s depth and proportions, the actual carat weight might differ slightly from what is estimated by the mm size alone.

Shape	MM Size	CT Weight
Baguette	2 x 1 mm	0.02 ct
Baguette	2 x 1.5 mm	0.04 ct
Baguette	2 x 1.75 mm	0.04 ct
Baguette	2.25 x 1.75 mm	0.04 ct
Baguette	2.25 x 2 mm	0.045 ct
Baguette	2.5 x 1 mm	0.045 ct
Baguette	2.5 x 1.25 mm	0.047 ct
Baguette	2.5 x 1.5 mm	0.05 ct
Baguette	3 x 1 mm	0.05 ct
Baguette	2.5 x 1.75 mm	0.055 ct
Baguette	2.5 x 2 mm	0.055 ct
Baguette	2.75 x 1.5 mm	0.055 ct
Baguette	3 x 1.25 mm	0.055 ct
Baguette	2.75 x 1.75 mm	0.06 ct
Baguette	2.75 x 2 mm	0.06 ct
Baguette	3 x 1.5 mm	0.06 ct
Baguette	3.25 x 1.25 mm	0.06 ct
Baguette	2.75 x 2.5 mm	0.065 ct
Baguette	3.25 x 1.5 mm	0.065 ct
Baguette	3.5 x 1 mm	0.065 ct
Baguette	3.5 x 1.25 mm	0.07 ct
Baguette	3.5 x 1.5 mm	0.07 ct
Baguette	4 x 1.25 mm	0.075 ct
Baguette	3 x 1.75 mm	0.08 ct
Baguette	3.25 x 1.75 mm	0.08 ct
Baguette	3.5 x 1.75 mm	0.08 ct
Baguette	4 x 1.5 mm	0.08 ct
Baguette	3 x 2 mm	0.10 ct
Baguette	4.5 x 1.5 mm	0.10 ct
Baguette	4 x 1.75 mm	0.11 ct
Baguette	3 x 2.5 mm	0.13 ct
Baguette	3.5 x 2 mm	0.13 ct
Baguette	3.25 x 2.5 mm	0.14 ct
Baguette	3.75 x 1.5 mm	0.14 ct
Baguette	4 x 2 mm	0.14 ct
Baguette	4.5 x 1.75 mm	0.14 ct
Baguette	5 x 1.5 mm	0.14 ct
Baguette	3.75 x 2 mm	0.145 ct
Baguette	3.5 x 2.5 mm	0.15 ct
Baguette	3.5 x 3 mm	0.15 ct
Baguette	5 x 1.75 mm	0.15 ct
Baguette	5.5 x 1.75 mm	0.16 ct
Baguette	4.5 x 2 mm	0.17 ct
Baguette	5.5 x 2 mm	0.18 ct
Baguette	5 x 2 mm	0.19 ct
Baguette	4 x 3 mm	0.20 ct
Baguette	4.5 x 2.5 mm	0.20 ct
Baguette	5.5 x 2.5 mm	0.23 ct
Baguette	5 x 2.5 mm	0.24 ct
Baguette	4.75 x 1.5 mm	0.27 ct
Baguette	4.75 x 2 mm	0.28 ct
Baguette	6 x 1.75 mm	0.28 ct
Baguette	4.5 x 3 mm	0.285 ct
Baguette	4.5 x 3.5 mm	0.30 ct
Baguette	5 x 3 mm	0.30 ct
Baguette	5.5 x 3 mm	0.30 ct
Baguette	6 x 2 mm	0.30 ct
Baguette	5 x 3.5 mm	0.33 ct
Baguette	5.5 x 3.5 mm	0.33 ct
Baguette	6 x 2.5 mm	0.33 ct
Baguette	5 x 4 mm	0.40 ct
Baguette	6 x 3 mm	0.40 ct
Cushion	4 mm	0.25 ct
Cushion	4.5 mm	0.36 ct
Cushion	5 mm	0.46 ct
Cushion	5.25 mm	0.56 ct
Cushion	5.5 mm	0.66 ct
Cushion	5.75 mm	0.76 ct
Cushion	6 mm	0.84 ct
Cushion	6.25 mm	0.93 ct
Cushion	6.5 mm	1.03 ct
Cushion	6.75 mm	1.24 ct
Cushion	7 mm	1.28 ct
Cushion	7.5 mm	1.67 ct
Cushion	14 mm	10.49 ct
Cushion	15 mm	12.89 ct
Cushion	8 mm	2.04 ct
Cushion	8.5 mm	2.43 ct
Cushion	9 mm	2.75 ct
Cushion	9.5 mm	3.35 ct
Cushion	10 mm	3.87 ct
Cushion	10.5 mm	4.41 ct
Cushion	11 mm	4.91 ct
Cushion	11.5 mm	5.85 ct
Cushion	12 mm	6.84 ct
Cushion	13 mm	8.51 ct
Emerald	3 x 2 mm	0.1 ct
Emerald	3.5 x 2 mm	0.12 ct
Emerald	4 x 2 mm	0.15 ct
Emerald	4 x 3 mm	0.20 ct
Emerald	5 x 3 mm	0.29 ct
Emerald	5.5 x 3.5 mm	0.46 ct
Emerald	5.5 x 4 mm	0.48 ct
Emerald	6 x 4 mm	0.66 ct
Emerald	6.5 x 4.5 mm	0.88 ct
Emerald	7 x 5 mm	1.06 ct
Emerald	7.25 x 5.25 mm	1.24 ct
Emerald	7.5 x 5.5 mm	1.45 ct
Emerald	8 x 6 mm	1.74 ct
Emerald	14 x 12 mm	11.26 ct
Emerald	16 x 12 mm	14.22 ct
Emerald	8.5 x 6.5 mm	2.17 ct
Emerald	9 x 7 mm	2.62 ct
Emerald	10 x 7 mm	3.01 ct
Emerald	9.5 x 7.5 mm	3.21 ct
Emerald	10 x 8 mm	3.79 ct
Emerald	11 x 9 mm	5.21 ct
Emerald	12 x 8 mm	5.34 ct
Emerald	12 x 10 mm	6 ct
Emerald	14 x 8 mm	6.25 ct
Emerald	13 x 9 mm	6.38 ct
Emerald	14 x 10 mm	8.48 ct
Emerald	13 x 11 mm	9.13 ct
Heart	3.5 mm	0.18 ct
Heart	4 mm	0.25 ct
Heart	4.25 mm	0.28 ct
Heart	4.5 mm	0.34 ct
Heart	4.75 mm	0.38 ct
Heart	5 mm	0.44 ct
Heart	5.5 mm	0.61 ct
Heart	6 mm	0.74 ct
Heart	6.25 mm	0.83 ct
Heart	6.5 mm	0.93 ct
Heart	7 mm	1.13 ct
Heart	7.5 mm	1.59 ct
Heart	8 mm	1.71 ct
Heart	15 mm	10.79 ct
Heart	16 mm	13.27 ct
Heart	18 mm	15.33 ct
Heart	9 mm	2.41 ct
Heart	9.5 mm	2.9 ct
Heart	10 mm	3.16 ct
Heart	11 mm	4.41 ct
Heart	12 mm	5.66 ct
Heart	12 mm	5.66 ct
Heart	13 mm	7.88 ct
Heart	14 mm	9.38 ct
Marquese	3 x 1.5 mm	0.025 ct
Marquese	3.5 x 1.75 mm	0.065 ct
Marquese	3.5 x 2 mm	0.07 ct
Marquese	4 x 2 mm	0.1 ct
Marquese	3.75 x 1.75 mm	0.11 ct
Marquese	4.25 x 2.25 mm	0.12 ct
Marquese	5 x 2.5 mm	0.14 ct
Marquese	5.5 x 2.75 mm	0.16 ct
Marquese	5.5 x 3 mm	0.18 ct
Marquese	5 x 3 mm	0.2 ct
Marquese	6.5 x 3 mm	0.23 ct
Marquese	6 x 3 mm	0.25 ct
Marquese	7 x 3 mm	0.3 ct
Marquese	7.5 x 3.5 mm	0.33 ct
Marquese	7 x 3.5 mm	0.35 ct
Marquese	8 x 4 mm	0.47 ct
Marquese	9 x 4.5 mm	0.71 ct
Marquese	9 x 5 mm	0.76 ct
Marquese	9.5 x 5 mm	0.85 ct
Marquese	10 x 5 mm	0.95 ct
Marquese	11 x 5.5 mm	1.25 ct
Marquese	11.5 x 6 mm	1.33 ct
Marquese	12 x 6 mm	1.62 ct
Marquese	12 x 6.5 mm	1.71 ct
Marquese	13 x 6.5 mm	2.11 ct
Marquese	14 x 7 mm	2.48 ct
Marquese	14 x 8 mm	3 ct
Marquese	15 x 7.5 mm	3.09 ct
Marquese	15 x 7 mm	3.12 ct
Marquese	7 x 4 mm	3.4 ct
Marquese	15 x 8 mm	3.44 ct
Marquese	16 x 8 mm	3.86 ct
Marquese	17 x 8.5 mm	4.88 ct
Marquese	17.5 x 10 mm	5.5 ct
Marquese	20 x 8 mm	7.08 ct
Marquese	20 x 10 mm	7.94 ct
Marquese	20 x 11 mm	9.5 ct
Oval	4.5 x 3.5 mm	0.21 ct
Oval	5 x 3 mm	0.21 ct
Oval	5.5 x 3.5 mm	0.33 ct
Oval	5 x 4 mm	0.35 ct
Oval	6 x 4 mm	0.43 ct
Oval	6 x 5 mm	0.61 ct
Oval	6.5 x 4.5 mm	0.65 ct
Oval	7 x 5 mm	0.76 ct
Oval	7.5 x 5.5 mm	0.98 ct
Oval	8 x 6 mm	1.21 ct
Oval	9 x 6 mm	1.41 ct
Oval	8.5 x 6.5 mm	1.46 ct
Oval	9 x 7 mm	1.86 ct
Oval	16 x 14 mm	11.88 ct
Oval	18 x 13 mm	12.86 ct
Oval	20 x 15 mm	14.96 ct
Oval	10 x 8 mm	2.54 ct
Oval	10.5 x 8.5 mm	2.88 ct
Oval	12 x 8 mm	2.99 ct
Oval	11 x 9 mm	3.85 ct
Oval	12 x 10 mm	5.05 ct
Oval	14 x 10 mm	5.81 ct
Oval	13 x 11 mm	6.05 ct
Oval	14 x 12 mm	8.21 ct
Oval	15 x 12 mm	8.76 ct
Oval	16 x 12 mm	9.32 ct
Pear	3 x 2 mm	0.13 ct
Pear	4 x 2.5 mm	0.18 ct
Pear	4 x 3 mm	0.21 ct
Pear	5 x 3 mm	0.25 ct
Pear	5 x 4 mm	0.35 ct
Pear	6 x 4 mm	0.39 ct
Pear	6.5 x 4.5 mm	0.57 ct
Pear	7 x 5 mm	0.71 ct
Pear	8 x 5 mm	0.81 ct
Pear	8.5 x 5.5 mm	1.08 ct
Pear	8 x 6 mm	1.25 ct
Pear	9 x 6 mm	1.33 ct
Pear	10 x 6 mm	1.71 ct
Pear	9 x 7 mm	1.75 ct
Pear	10 x 7 mm	1.8 ct
Pear	18 x 13 mm	10.21 ct
Pear	10 x 8 mm	2.46 ct
Pear	11 x 7.50 mm	2.61 ct
Pear	13 x 8 mm	2.98 ct
Pear	11 x 8 mm	3 ct
Pear	12 x 8 mm	3 ct
Pear	12 x 7 mm	3.12 ct
Pear	12 x 9 mm	3.44 ct
Pear	14 x 8 mm	3.47 ct
Pear	13 x 9 mm	4.11 ct
Pear	14 x 9 mm	4.25 ct
Pear	15 x 9 mm	5.06 ct
Pear	14 x 10 mm	5.41 ct
Pear	13 x 11 mm	5.65 ct
Pear	15 x 10 mm	5.75 ct
Pear	16 x 9 mm	5.86 ct
Pear	16 x 10 mm	6.27 ct
Pear	17 x 10 mm	6.46 ct
Pear	15 x 11 mm	7.36 ct
Pear	18 x 11 mm	8.14 ct
Pear	16 x 12 mm	8.99 ct
Pear	18 x 12 mm	9.35 ct
Princess	1.5 mm	0.015 ct
Princess	1.75 mm	0.03 ct
Princess	2 mm	0.06 ct
Princess	2.25 mm	0.08 ct
Princess	2.5 mm	0.1 ct
Princess	2.75 mm	0.13 ct
Princess	3 mm	0.18 ct
Princess	3.25 mm	0.26 ct
Princess	3.5 mm	0.29 ct
Princess	3.75 mm	0.31 ct
Princess	4 mm	0.39 ct
Princess	4.25 mm	0.44 ct
Princess	4.5 mm	0.56 ct
Princess	4.75 mm	0.64 ct
Princess	5 mm	0.71 ct
Princess	5.25 mm	0.75 ct
Princess	5.5 mm	0.99 ct
Princess	5.75 mm	1.11 ct
Princess	6 mm	1.24 ct
Princess	6.25 mm	1.39 ct
Princess	6.5 mm	1.59 ct
Princess	6.75 mm	1.75 ct
Princess	7 mm	1.96 ct
Princess	7.25 mm	2.01 ct
Princess	7.5 mm	2.4 ct
Princess	7.75 mm	2.74 ct
Princess	8 mm	3.01 ct
Princess	8.25 mm	3.24 ct
Princess	8.5 mm	3.67 ct
Princess	8.75 mm	4.1 ct
Princess	9 mm	4.12 ct
Princess	9.5 mm	5.09 ct
Princess	9.75 mm	5.36 ct
Princess	10 mm	5.62 ct
Princess	10.25 mm	5.76 ct
Princess	10.5 mm	5.99 ct
Princess	11 mm	7.44 ct
Princess	11.5 mm	9.44 ct
Princess	12 mm	9.52 ct
Radiant	5 x 3 mm	0.31 ct
Radiant	4.5 x 3.5 mm	0.34 ct
Radiant	6 x 3 mm	0.41 ct
Radiant	6 x 4 mm	0.60 ct
Radiant	6.5 x 4.5 mm	0.83 ct
Radiant	7 x 5 mm	1.14 ct
Radiant	7.25 x 5.25 mm	1.24 ct
Radiant	7.5 x 5.5 mm	1.47 ct
Radiant	8 x 6 mm	1.74 ct
Radiant	13.5 x 11.5 mm	10.19 ct
Radiant	15 x 11 mm	11.48 ct
Radiant	14 x 12 mm	12.14 ct
Radiant	16 x 12 mm	14.22 ct
Radiant	8.5 x 6.5 mm	2.25 ct
Radiant	9 x 7 mm	2.62 ct
Radiant	9.5 x 7.5 mm	3.18 ct
Radiant	10 x 7 mm	3.31 ct
Radiant	10 x 8 mm	3.49 ct
Radiant	11 x 9 mm	5.05 ct
Radiant	12 x 9 mm	6.06 ct
Radiant	11.5 x 10 mm	6.45 ct
Radiant	13 x 9 mm	6.54 ct
Radiant	12 x 10 mm	6.79 ct
Radiant	14 x 10 mm	8.47 ct
Radiant	13 x 11 mm	9.33 ct
Round	0.8 mm	0.0025 ct
Round	1 mm	0.005 ct
Round	1.15 mm	0.0067 ct
Round	1.10 mm	0.0075 ct
Round	1.25 mm	0.01 ct
Round	1.3 mm	0.01 ct
Round	1.5 mm	0.015 ct
Round	1.75 mm	0.02 ct
Round	1.8 mm	0.025 ct
Round	2 mm	0.03 ct
Round	2.25 mm	0.04 ct
Round	2.5 mm	0.06 ct
Round	2.75 mm	0.08 ct
Round	3 mm	0.11 ct
Round	3.25 mm	0.14 ct
Round	3.5 mm	0.17 ct
Round	3.75 mm	0.21 ct
Round	4 mm	0.25 ct
Round	4.25 mm	0.28 ct
Round	4.5 mm	0.36 ct
Round	4.75 mm	0.44 ct
Round	5 mm	0.46 ct
Round	5.25 mm	0.56 ct
Round	5.5 mm	0.66 ct
Round	5.75 mm	0.76 ct
Round	6 mm	0.84 ct
Round	6.25 mm	0.93 ct
Round	6.5 mm	1.03 ct
Round	6.75 mm	1.24 ct
Round	7 mm	1.28 ct
Round	7.25 mm	1.49 ct
Round	7.5 mm	1.67 ct
Round	7.75 mm	1.75 ct
Round	14 mm	10.49 ct
Round	15 mm	12.89 ct
Round	16 mm	16.06 ct
Round	8 mm	2.04 ct
Round	8.25 mm	2.11 ct
Round	8.5 mm	2.43 ct
Round	8.75 mm	2.55 ct
Round	9 mm	2.75 ct
Round	9.25 mm	3.05 ct
Round	9.5 mm	3.35 ct
Round	9.75 mm	3.61 ct
Round	10 mm	3.87 ct
Round	10.25 mm	4.16 ct
Round	10.5 mm	4.41 ct
Round	10.75 mm	4.57 ct
Round	11 mm	4.91 ct
Round	11.25 mm	5.49 ct
Round	11.5 mm	5.85 ct
Round	12 mm	6.84 ct
Round	12.25 mm	7.26 ct
Round	12.5 mm	7.36 ct
Round	12.75 mm	7.52 ct
Round	13 mm	8.51 ct
Round	13.5 mm	9.53 ct
Shape	MM Size	CT Weight