These are the standard sizes we have used on a lot of our mounts. You can download a more comprehensive list here too.
Imperial sizes (inches) | Metric sizes (mms) |
6 x 4 | 178 x 128 |
7 x 5 | 153 x 102 |
10 x 8 | 254 x 203 |
10 x 12 | 254 x 305 |
11 x 14 | 279 x 356 |
12 x 16 | 254 x 406 |
14 x 18 | 356 x 457 |
16 x 20 | 406 x 508 |