We’ve estimated the average side length (mm) for princess cut diamonds using measurements from a sample of diamonds listed for sale. Relative sizes for each carat weight are illustrated in the figure below the table.
| Carat | Side Length | SD | N |
|---|---|---|---|
| 0.3 ct | 3.72 mm | 0.07 | 183 |
| 0.4 ct | 4.09 mm | 0.088 | 124 |
| 0.5 ct | 4.37 mm | 0.107 | 417 |
| 0.6 ct | 4.6 mm | 0.106 | 111 |
| 0.7 ct | 4.84 mm | 0.116 | 519 |
| 0.8 ct | 5.03 mm | 0.122 | 273 |
| 0.9 ct | 5.22 mm | 0.11 | 552 |
| 1.0 ct | 5.46 mm | 0.136 | 1283 |
| 1.1 ct | 5.7 mm | 0.136 | 70 |
| 1.2 ct | 5.8 mm | 0.169 | 392 |
| 1.3 ct | 6 mm | 0.162 | 84 |
| 1.4 ct | 6.2 mm | 0.187 | 53 |
| 1.5 ct | 6.27 mm | 0.158 | 311 |
| 1.6 ct | 6.44 mm | 0.135 | 31 |
| 1.7 ct | 6.55 mm | 0.152 | 153 |
| 1.8 ct | 6.67 mm | 0.129 | 46 |
| 1.9 ct | 6.85 mm | 0.18 | 31 |
| 2.0 ct | 6.93 mm | 0.158 | 197 |
| 2.1 ct | 7.09 mm | 0.121 | 13 |
| 2.2 ct | 7.17 mm | 0.103 | 9 |
| 2.3 ct | 7.3 mm | 0.15 | 6 |
| 2.4 ct | 7.28 mm | 0.08 | 5 |
| 2.5 ct | 7.42 mm | 0.175 | 50 |
| 2.6 ct | 7.54 mm | 0.124 | 6 |
| 2.7 ct | 7.63 mm | 0.142 | 11 |
| 2.8 ct | 7.81 mm | 0.12 | 4 |
| 2.9 ct | NA mm | NA | 0 |
| 3.0 ct | 7.93 mm | 0.185 | 51 |
| 3.1 ct | 7.89 mm | 0.119 | 5 |
| 3.2 ct | 8.15 mm | 0.163 | 2 |
| 3.3 ct | NA mm | NA | 0 |
| 3.4 ct | 8.26 mm | 0 | 1 |
| 3.5 ct | 8.36 mm | 0.166 | 8 |
