The circumference of the head just above the ears, measured in centimetres, is used to size riding hats and skull caps. Riding hats and skull caps are sized differently and the table below shows the range of head measurements with the corresponding riding hat and skull cap sizes.
| Head Measurement | Riding Hat Size | Skull Cap Size |
| 49cm | 6 | 000 |
| 50cm | 6 1/8 | 000 1/2 |
| 51cm | 6 1/4 | 00 |
| 52cm | 6 3/8 | 00 1/2 |
| 53cm | 6 1/2 | 0 |
| 54cm | 6 5/8 | 0 1/2 |
| 55cm | 6 3/4 | 1 |
| 56cm | 6 7/8 | 1 1/2 |
| 57cm | 7 | 2 |
| 58cm | 7 1/8 | 2 1/2 |
| 59cm | 7 1/4 | 3 |
| 60cm | 7 3/8 | 3 1/2 |
| 61cm | 7 1/2 | 4 |
| 62cm | 7 5/8 | 4 1/2 |
| 63cm | 7 3/4 | 5 |
