Diamond Size Chart (Round)
Carat to mm size chart for round-cut Diamond, from 0.25ct to 40ct. The chart is interactive, meaning you can click on any stone to view it directly in the size simulator.
Gem sizes are shown in actual, real-world size, provided your device screen size is in diagonal. If this is not correct, change it here:
Gem sizes are shown in actual, real-world size, provided your device screen size is in diagonal. If this is not correct, change it here:
Actual size is set for screen
Gemstone:
Shape:
Diamond Size Chart (Round Cut)
0.25ct
4.09×4.09 mm
4.09×4.09 mm
0.5ct
5.16×5.16 mm
5.16×5.16 mm
0.75ct
5.91×5.91 mm
5.91×5.91 mm
1ct
6.5×6.5 mm
6.5×6.5 mm
1.25ct
7×7 mm
7×7 mm
1.5ct
7.44×7.44 mm
7.44×7.44 mm
1.75ct
7.83×7.83 mm
7.83×7.83 mm
2ct
8.19×8.19 mm
8.19×8.19 mm
2.5ct
8.82×8.82 mm
8.82×8.82 mm
3ct
9.37×9.37 mm
9.37×9.37 mm
3.5ct
9.87×9.87 mm
9.87×9.87 mm
4ct
10.32×10.32 mm
10.32×10.32 mm
4.5ct
10.73×10.73 mm
10.73×10.73 mm
5ct
11.11×11.11 mm
11.11×11.11 mm
5.5ct
11.47×11.47 mm
11.47×11.47 mm
6ct
11.81×11.81 mm
11.81×11.81 mm
6.5ct
12.13×12.13 mm
12.13×12.13 mm
7ct
12.43×12.43 mm
12.43×12.43 mm
7.5ct
12.72×12.72 mm
12.72×12.72 mm
8ct
13×13 mm
13×13 mm
8.5ct
13.27×13.27 mm
13.27×13.27 mm
9ct
13.52×13.52 mm
13.52×13.52 mm
9.5ct
13.77×13.77 mm
13.77×13.77 mm
10ct
14×14 mm
14×14 mm
11ct
14.46×14.46 mm
14.46×14.46 mm
12ct
14.88×14.88 mm
14.88×14.88 mm
13ct
15.28×15.28 mm
15.28×15.28 mm
14ct
15.67×15.67 mm
15.67×15.67 mm
15ct
16.03×16.03 mm
16.03×16.03 mm
16ct
16.38×16.38 mm
16.38×16.38 mm
17ct
16.71×16.71 mm
16.71×16.71 mm
18ct
17.03×17.03 mm
17.03×17.03 mm
19ct
17.34×17.34 mm
17.34×17.34 mm
20ct
17.64×17.64 mm
17.64×17.64 mm
22ct
18.21×18.21 mm
18.21×18.21 mm
24ct
18.75×18.75 mm
18.75×18.75 mm
26ct
19.26×19.26 mm
19.26×19.26 mm
28ct
19.74×19.74 mm
19.74×19.74 mm
30ct
20.2×20.2 mm
20.2×20.2 mm
33ct
20.85×20.85 mm
20.85×20.85 mm
36ct
21.46×21.46 mm
21.46×21.46 mm
40ct
22.23×22.23 mm
22.23×22.23 mm
Length-to-width ratio: 1, Color:
Download Chart
Note: If you want to cut out the shapes and try them on your finger, print out the PDF chart. The image (png) chart will not print at actual size.
Carat-to-MM Conversion Table
Use this conversion table to quickly convert round-cut Diamond carat weights to their approximate millimeter (mm) sizes:
| Carat Weight | MM Size |
|---|---|
| 0.25 ct | 4.09×4.09 mm |
| 0.5 ct | 5.16×5.16 mm |
| 0.75 ct | 5.91×5.91 mm |
| 1 ct | 6.5×6.5 mm |
| 1.25 ct | 7×7 mm |
| 1.5 ct | 7.44×7.44 mm |
| 1.75 ct | 7.83×7.83 mm |
| 2 ct | 8.19×8.19 mm |
| 2.5 ct | 8.82×8.82 mm |
| 3 ct | 9.37×9.37 mm |
| 3.5 ct | 9.87×9.87 mm |
| 4 ct | 10.32×10.32 mm |
| 4.5 ct | 10.73×10.73 mm |
| 5 ct | 11.11×11.11 mm |
| 5.5 ct | 11.47×11.47 mm |
| 6 ct | 11.81×11.81 mm |
| 6.5 ct | 12.13×12.13 mm |
| 7 ct | 12.43×12.43 mm |
| 7.5 ct | 12.72×12.72 mm |
| 8 ct | 13×13 mm |
| 8.5 ct | 13.27×13.27 mm |
| Carat Weight | MM Size |
|---|---|
| 9 ct | 13.52×13.52 mm |
| 9.5 ct | 13.77×13.77 mm |
| 10 ct | 14×14 mm |
| 11 ct | 14.46×14.46 mm |
| 12 ct | 14.88×14.88 mm |
| 13 ct | 15.28×15.28 mm |
| 14 ct | 15.67×15.67 mm |
| 15 ct | 16.03×16.03 mm |
| 16 ct | 16.38×16.38 mm |
| 17 ct | 16.71×16.71 mm |
| 18 ct | 17.03×17.03 mm |
| 19 ct | 17.34×17.34 mm |
| 20 ct | 17.64×17.64 mm |
| 22 ct | 18.21×18.21 mm |
| 24 ct | 18.75×18.75 mm |
| 26 ct | 19.26×19.26 mm |
| 28 ct | 19.74×19.74 mm |
| 30 ct | 20.2×20.2 mm |
| 33 ct | 20.85×20.85 mm |
| 36 ct | 21.46×21.46 mm |
| 40 ct | 22.23×22.23 mm |