Diamonds can be measured in both carat weight and millimeter. While diamonds are purchased based on carat weight — the standard unit of measurement for loose diamonds — it’s important to consider millimeter measurements and ratios to choose the best possible option for your budget.
Round Cut Diamond Size Chart (MM)
Wondering what a 1 carat round diamond looks link on a hand? Our round diamond size chart will help you convert millimeter (mm) size to carat size for round cut diamonds.
| Round MM Size | Round Carat Weight |
|---|---|
| 0.8 mm. | 0.0025 ct. |
| 1 mm. | 0.005 ct. |
| 1.1 mm. | 0.0067 ct. |
| 1.2 mm. | 0.009 ct. |
| 1.25 mm. | 0.01 ct. |
| 1.3 mm. | 0.01 ct. |
| 1.5 mm. | 0.015 ct. |
| 1.75 mm. | 0.02 ct. |
| 1.8 mm. | 0.025 ct. |
| 2 mm. | 0.03 ct. |
| 2.2 mm. | 0.04 ct. |
| 2.5 mm. | 0.06 ct. |
| 2.75 mm. | 0.08 ct. |
| 3 mm. | 0.10 ct. |
| 3.25 mm. | 0.14 ct. |
| 3.5 mm. | 0.17 ct. |
| 3.75 mm. | 0.21 ct. |
| 4 mm. | 0.25 ct. |
| 4.25 mm. | 0.28 ct. |
| 4.5 mm. | 0.36 ct. |
| 4.75 mm. | 0.44 ct. |
| 5.0 mm. | 0.50 ct. |
| 5.25 mm. | 0.56 ct. |
| 5.5 mm. | 0.66 ct. |
| 5.75 mm. | 0.75 ct. |
| 6 mm. | 0.84 ct. |
| 6.25 mm. | 0.93 ct. |
| 6.5 mm. | 1.00 ct. |
| 6.8 mm. | 1.25 ct. |
| Round MM Size | Round Carat Weight |
|---|---|
| 7 mm. | 1.30 ct. |
| 7.3 mm. | 1.50 ct. |
| 7.5 mm. | 1.67 ct. |
| 7.75 mm. | 1.75 ct. |
| 8 mm. | 2.00 ct. |
| 8.25 mm. | 2.11 ct. |
| 8.5 mm. | 2.43 ct. |
| 8.7 mm. | 2.50 ct. |
| 9 mm. | 2.75 ct. |
| 9.1 mm. | 3.00 ct. |
| 9.5 mm. | 3.35 ct. |
| 9.75 mm. | 3.61 ct. |
| 10 mm. | 3.87 ct. |
| 10.25 mm. | 4.16 ct. |
| 10.5 mm. | 4.41 ct. |
| 10.75 mm. | 4.57 ct. |
| 11 mm. | 4.91 ct. |
| 11.25 mm. | 5.49 ct. |
| 11.5 mm. | 5.85 ct. |
| 12 mm. | 6.84 ct. |
| 12.25 mm. | 7.26 ct. |
| 12.5 mm. | 7.36 ct. |
| 12.75 mm. | 7.52 ct. |
| 13 mm. | 8.51 ct. |
| 13.5 mm. | 9.53 ct. |
| 14 mm. | 10.49 ct. |
| 15 mm. | 12.89 ct. |
| 16 mm. | 16.06 ct. |