Diamond mm to carat conversion chart

The table sets out the approximate relationship between the size of a diamond and its Carat weight.

Round Stones
Milimeters	Carat weight	Points
1.0	0.005	0.5
1.3	0.01	1
1.5	0.02	1.5
1.7	0.02	1
1.8	0.03	2.5
2.0	0.03	3
2.1	0.04	3.5
2.2	0.04	4
2.4	0.05	5
2.5	0.06	6
2.7	0.07	7
2.8	0.08	8
2.9	0.09	9
3.0	0.10	10
3.1	0.11	11
3.2	0.12	12
3.3	0.14	14
3.4	0.15	15
3.5	0.16	16
3.6	0.17	17
3.7	0.18	18
3.8	0.20	20
3.9	0.22	22
4.0	0.25	25
4.2	0.30	30
4.4	0.33	33
4.5	0.35	35
4.6	0.38	38
4.8	0.40	40
5.0	0.50	50
5.4	0.60	60
5.5	0.63	63
5.6	0.65	65
6.0	0.75	75
6.4	0.95	95
6.6	1.00	100
6.8	1.17	117
7.0	1.25	125
7.2	1.33	133
7.5	1.55	155
7.8	1.75	175
8.0	2.00	200
8.4	2.15	215
8.6	2.25	225
9.0	2.75	275
9.4	3.00	300
9.6	3.15	315
9.8	3.35	335
10.0	3.50	350
10.2	3.75	375
10.4	4.00	400
10.6	4.25	425
10.8	4.50	450
11.0	4.75	475
11.2	5.00	500
12.0	6.50	650

Oval Cut
Milimeters	Carat weight	Points
4 x 3	0.20	20
5 x 3	0.25	25
5 x 3.5	0.33	33
5 x 4	0.40	40
6 x 4	0.50	50
6.5 x 4.5	0.65	65
7 x 5	0.75	75
7.5 x 5.5	1.00	100
8 x 6	1.25	125
8.5 x 6.5	1.50	150
9 x 6	1.75	175
9 x 7	2.00	200
9.5 x 7.5	2.50	250
10 x 8	3.00	300
10 x 8.5	3.50	350
11 x 9	4.00	400
11 x 9.5	4.50	450
12 x 10	5.00	500

Marquise Cut
Milimeters	Carat weight	Points
3.5 x 1.5	0.07	7
4 x 2	0.10	10
5 x 2	0.20	20
5 x 3	0.22	22
5.5 x 2.5	0.25	25
6 x 6	0.30	30
7 x 3	0.35	35
7 x 3.5	0.38	38
7 x 4	0.40	40
8 x 4	0.50	50
8.5 x 4.5	0.65	65
9 x 4	0.70	70
9 x 4.5	0.75	75
9 x 5	0.80	80
9.5 x 4.5	0.85	85
10 x 4.75	1.00	100
10 x 5	1.25	125
11 x 5	1.50	150
11 x 5.5	1.65	165
12 x 6	2.00	200
13 x 5.5	2.50	250
13 x 6	2.65	265
14 x 6.5	2.87	287
14 x 7	3.00	300
15 x 7	3.75	375
16 x 8	4.50	450
18 x 9	7.00	700
20 x 10	10.00	1000

Princess Cut
Milimeters	Carat weight	Points
2.0	0.06	6
2.3	0.08	8
2.5	0.10	10
2.8	0.13	13
3.0	0.15	15
3.3	0.20	20
3.5	0.23	23
3.8	0.25	25
4.0	0.30	30
4.4	0.35	35
4.5	0.40	40
4.8	0.50	50
5.0	0.63	63
5.3	0.75	75
5.5	1.00	100
6.0	1.25	125
7.0	1.60	160
8.0	2.25	225

Emerald Cut
Milimeters	Carat weight	Points
4 x 3	0.20	20
5 x 3	0.25	25
6 x4	0.50	50
6.5 x 4.5	0.75	75
7 x 5	1.00	100
8 x 6	1.50	150
8.5 x 6.5	2.00	200
9 x 7	2.50	250
10 x 8	3.00	300
11 x 9	4.00	400
12 x 10	5.00	500

Pear Cut
Milimeters	Carat weight	Points
4 x 2	0.20	20
5 x 3	0.30	30
6 x 4	0.50	50
7 x 5	0.75	75
8 x 5	1.00	100
9 x 6	1.50	150
10 x 7	2.00	200
12 x 7	2.50	250
12 x 8	3.00	300
13 x 8	3.50	350
14 x 8	4.00	400
15 x 9	5.00	500

Heart Shaped Stones
Milimeters	Carat weight	Points
4×4	0.25	25
5×5	0.50	50
5.5×5.5	0.65	65
6×6	0.75	75
6.5×6.5	1.00	100
7×7	1.50	150
8×8	2.00	200
8.5×8.5	2.50	250
9×9	3.00	300
9.5×9.5	3.50	350
10×10	4.00	400
10.5×10.5	4.50	450
11×11	5.00	500

Tapered Baguette Cut Stones
Milimeters	Carat weight	Points
3x1x0.05	0.04	4
3x1x5.1	0.06	6
3.5×1.5×1	0.09	9
3.5×2.5×1	0.15	15
4x2x1	0.12	12
4.5x2x1	0.15	15
5x2x1.5	0.20	20

Baguette Cut
Milimeters	Carat weight	Points
3×1.5	0.05	5
3×2	0.09	9
3.5×2	0.11	11
4×2	0.16	16
5×2	0.20	20
5×2.5	0.25	25
5×3	0.30	30
6×2	0.30	30
6×3	0.40	40
6×4	0.60	60

Diamond mm to carat conversion chart

Round Stones

Oval Cut

Marquise Cut

Princess Cut

Emerald Cut

Pear Cut

Heart Shaped Stones