| Hemel Hempstead to Nottingham | 87.79 mi (141.29 km) |
| Hemel Hempstead to Nuneaton | 68.02 mi (109.47 km) |
| Hemel Hempstead to Oadby | 63.87 mi (102.79 km) |
| Hemel Hempstead to Oakengates | 106.18 mi (170.88 km) |
| Hemel Hempstead to Oakham | 64.40 mi (103.64 km) |
| Hemel Hempstead to Oldbury | 83.70 mi (134.70 km) |
| Hemel Hempstead to Oldham | 141.76 mi (228.13 km) |
| Hemel Hempstead to Ollerton | 102.66 mi (165.21 km) |
| Hemel Hempstead to Olton | 73.89 mi (118.91 km) |
| Hemel Hempstead to Omagh | 343.62 mi (553.00 km) |
| Hemel Hempstead to Ormesby | 195.47 mi (314.57 km) |
| Hemel Hempstead to Ormskirk | 161.14 mi (259.34 km) |
| Hemel Hempstead to Orpington | 35.76 mi (57.55 km) |
| Hemel Hempstead to Ossett | 141.05 mi (226.99 km) |
| Hemel Hempstead to Oswaldtwistle | 159.32 mi (256.40 km) |
