| Middlesex to Oerlinghausen | 3,827.07 mi (6,159.08 km) |
| Middlesex to Oestrich-Winkel | 3,855.90 mi (6,205.47 km) |
| Middlesex to Offenburg | 3,897.75 mi (6,272.82 km) |
| Middlesex to Oftersheim | 3,897.86 mi (6,273.01 km) |
| Middlesex to Ohrdruf | 3,940.79 mi (6,342.08 km) |
| Middlesex to Ohringen | 3,940.18 mi (6,341.10 km) |
| Middlesex to Olbernhau | 4,047.59 mi (6,513.96 km) |
| Middlesex to Olching | 4,045.18 mi (6,510.08 km) |
| Middlesex to Oldenburg | 3,777.68 mi (6,079.59 km) |
| Middlesex to Oldenburg in Holstein | 3,846.83 mi (6,190.87 km) |
| Middlesex to Olfen | 3,783.58 mi (6,089.08 km) |
| Middlesex to Olpe | 3,820.56 mi (6,148.60 km) |
| Middlesex to Olsberg | 3,837.03 mi (6,175.11 km) |
| Middlesex to Oranienburg | 3,979.33 mi (6,404.11 km) |
| Middlesex to Ortenberg | 3,888.10 mi (6,257.29 km) |
