Os1st Socks Fit Guide
Os1st Socks Merino Will & Nekkid
| Sizing | US Women | Us Men | UK | European |
| Small | 5-7.5 | 4.5-6.5 | 2.5-5 | 35.5-38.5 |
| Medium | 8-11 | 7-10 | 6-9 | 39-43.5 |
| Large | 11.5+ | 10.5-13 | 9.5-12.5 | 44-48 |
| Extra Large | N/A | 13.5+ | 13+ | 49+ |
Os1st Plantar Fasciitis
| Sizing | US Women | Us Men | UK | European |
| Small | 4-6.5 | 3-3.5 | 2-4.5 | 34-37 |
| Medium | 7-10.5 | 6-9.5 | 4.5-8.5 | 37.5-43 |
| Large | 10.5+ | 10-13 | 9-12 | 12.5+ |
| Extra Large | N/A | 13.5+ | 12.5+ | 48+ |
