Princess Cut Diamond Carat Size Chart

We’ve estimated the average side length (mm) for princess cut diamonds using measurements listed on James Allen.  Note: princess diamonds that have been cut to maximize beauty rather than carat weight will have an average side length approximately 0.1mm smaller than the numbers listed below.  This difference is well worth the improvement in brilliance, fire, and scintillation.

Relative sizes for each carat weight are illustrated in the figure below the table.

Average Side Length of Princess Cut Diamonds
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

Princess diamond carat to side length mm figure