| Middlesex to Nuth | 3,745.26 mi (6,027.41 km) |
| Middlesex to Oegstgeest | 3,656.33 mi (5,884.29 km) |
| Middlesex to Oirschot | 3,706.64 mi (5,965.27 km) |
| Middlesex to Oisterwijk | 3,700.52 mi (5,955.41 km) |
| Middlesex to Oldebroek | 3,706.10 mi (5,964.39 km) |
| Middlesex to Oldenzaal | 3,749.96 mi (6,034.98 km) |
| Middlesex to Ommen | 3,724.59 mi (5,994.15 km) |
| Middlesex to Oosterend | 3,698.61 mi (5,952.33 km) |
| Middlesex to Oosterhout | 3,685.31 mi (5,930.93 km) |
| Middlesex to Oosterwolde | 3,707.65 mi (5,966.89 km) |
| Middlesex to Oostzaan | 3,666.61 mi (5,900.83 km) |
| Middlesex to Opmeer | 3,662.66 mi (5,894.49 km) |
| Middlesex to Oss | 3,708.42 mi (5,968.13 km) |
| Middlesex to Oud-Beijerland | 3,662.74 mi (5,894.61 km) |
| Middlesex to Oudenbosch | 3,673.37 mi (5,911.71 km) |
