Size guide for Mares FF (Full Foot) fins with a foot pocket. These fins are designed primarily for snorkelling or warm water diving and barefoot, they do not have a deep enough foot pocket to accept a sock.
| Labelled Size Single EU Size | EU Size | UK Size |
| 36 | 36 – 37 | 3 – 4 |
| 38 | 38 – 39 | 5 – 6 |
| 40 | 40 – 41 | 6.5 – 7.5 |
| 42 | 42 – 43 | 8 – 9 |
| 44 | 44 – 45 | 9.5 – 10.5 |
| 46 | 46 – 47 | 11 – 12 |