Carat is a measure of weight, not size. Two stones of identical carat can look noticeably different on a hand, because shape decides how that weight is distributed.
Every figure here is calculated by the same functions the tool itself uses, from standard per-shape weight factors and typical proportions. Real stones vary — a certificate gives the actual measurements for a particular diamond, and those are what you should use when it matters.
| Weight | Round | Oval | Cushion | Pear | Marquise | Emerald | Radiant | Princess | Asscher |
|---|---|---|---|---|---|---|---|---|---|
| 0.25 ct | 4.05 × 4.05 | 4.99 × 3.56 | 3.68 × 3.50 | 5.32 × 3.43 | 6.15 × 3.24 | 4.55 × 3.25 | 4.03 × 3.36 | 3.46 × 3.46 | 3.58 × 3.58 |
| 0.50 ct | 5.11 × 5.11 | 6.28 × 4.49 | 4.63 × 4.41 | 6.70 × 4.32 | 7.75 × 4.08 | 5.73 × 4.10 | 5.08 × 4.23 | 4.35 × 4.35 | 4.51 × 4.51 |
| 0.75 ct | 5.85 × 5.85 | 7.19 × 5.14 | 5.30 × 5.05 | 7.67 × 4.95 | 8.87 × 4.67 | 6.56 × 4.69 | 5.81 × 4.84 | 4.98 × 4.98 | 5.17 × 5.17 |
| 1.00 ct | 6.44 × 6.44 | 7.91 × 5.65 | 5.84 × 5.56 | 8.44 × 5.44 | 9.77 × 5.14 | 7.22 × 5.16 | 6.39 × 5.33 | 5.49 × 5.49 | 5.69 × 5.69 |
| 1.25 ct | 6.93 × 6.93 | 8.53 × 6.09 | 6.29 × 5.99 | 9.09 × 5.86 | 10.52 × 5.54 | 7.78 × 5.56 | 6.89 × 5.74 | 5.91 × 5.91 | 6.12 × 6.12 |
| 1.50 ct | 7.37 × 7.37 | 9.06 × 6.47 | 6.68 × 6.36 | 9.66 × 6.23 | 11.18 × 5.88 | 8.27 × 5.91 | 7.32 × 6.10 | 6.28 × 6.28 | 6.51 × 6.51 |
| 2.00 ct | 8.11 × 8.11 | 9.97 × 7.12 | 7.35 × 7.00 | 10.63 × 6.86 | 12.30 × 6.48 | 9.10 × 6.50 | 8.06 × 6.71 | 6.91 × 6.91 | 7.16 × 7.16 |
| 2.50 ct | 8.73 × 8.73 | 10.74 × 7.67 | 7.92 × 7.55 | 11.45 × 7.39 | 13.25 × 6.98 | 9.80 × 7.00 | 8.68 × 7.23 | 7.44 × 7.44 | 7.72 × 7.72 |
| 3.00 ct | 9.28 × 9.28 | 11.41 × 8.15 | 8.42 × 8.02 | 12.17 × 7.85 | 14.08 × 7.41 | 10.42 × 7.44 | 9.22 × 7.69 | 7.91 × 7.91 | 8.20 × 8.20 |
This is the number that actually decides how large a stone looks from above, and it is where shape matters most. Compare across a row: at the same weight, elongated shapes generally spread wider than a round, while deep shapes hide weight underneath.
| Weight | Round | Oval | Cushion | Pear | Marquise | Emerald | Radiant | Princess | Asscher |
|---|---|---|---|---|---|---|---|---|---|
| 0.25 ct | 12.9 | 13.9 | 11.5 | 12.4 | 14.0 | 14.3 | 13.0 | 11.9 | 12.3 |
| 0.50 ct | 20.5 | 22.1 | 18.3 | 19.7 | 22.2 | 22.7 | 20.7 | 19.0 | 19.4 |
| 0.75 ct | 26.8 | 29.0 | 24.0 | 25.8 | 29.1 | 29.8 | 27.1 | 24.8 | 25.5 |
| 1.00 ct | 32.5 | 35.1 | 29.0 | 31.3 | 35.2 | 36.1 | 32.8 | 30.1 | 30.9 |
| 1.25 ct | 37.7 | 40.8 | 33.7 | 36.3 | 40.9 | 41.9 | 38.1 | 34.9 | 35.8 |
| 1.50 ct | 42.6 | 46.0 | 38.0 | 41.0 | 46.2 | 47.3 | 43.0 | 39.4 | 40.5 |
| 2.00 ct | 51.6 | 55.8 | 46.1 | 49.6 | 55.9 | 57.3 | 52.1 | 47.8 | 49.0 |
| 2.50 ct | 59.9 | 64.7 | 53.5 | 57.6 | 64.9 | 66.4 | 60.4 | 55.4 | 56.9 |
| 3.00 ct | 67.6 | 73.1 | 60.4 | 65.0 | 73.3 | 75.0 | 68.2 | 62.6 | 64.2 |
A table can tell you a stone is 7.91 × 5.65 mm. It cannot tell you what that looks like on your hand, which is the thing people actually want to know.
See it on your own hand →