| Hemel Hempstead to Oberkirch | 438.79 mi (706.16 km) |
| Hemel Hempstead to Obernburg am Main | 439.65 mi (707.54 km) |
| Hemel Hempstead to Obernkirchen | 408.97 mi (658.17 km) |
| Hemel Hempstead to Oberschleissheim | 585.83 mi (942.81 km) |
| Hemel Hempstead to Oberstdorf | 566.50 mi (911.70 km) |
| Hemel Hempstead to Obertraubling | 588.42 mi (946.98 km) |
| Hemel Hempstead to Obertshausen | 421.35 mi (678.10 km) |
| Hemel Hempstead to Oberursel | 407.52 mi (655.85 km) |
| Hemel Hempstead to Ochsenfurt | 482.90 mi (777.16 km) |
| Hemel Hempstead to Ochsenhausen | 527.98 mi (849.70 km) |
| Hemel Hempstead to Ochtrup | 327.32 mi (526.77 km) |
| Hemel Hempstead to Odenthal | 330.65 mi (532.12 km) |
| Hemel Hempstead to Oelde | 368.17 mi (592.50 km) |
| Hemel Hempstead to Oelsnitz | 555.41 mi (893.84 km) |
| Hemel Hempstead to Oer-Erkenschwick | 330.54 mi (531.96 km) |
