| Porvoo to Oegstgeest | 984.20 mi (1,583.92 km) |
| Porvoo to Oirschot | 992.22 mi (1,596.82 km) |
| Porvoo to Oisterwijk | 991.07 mi (1,594.97 km) |
| Porvoo to Oldebroek | 927.71 mi (1,493.01 km) |
| Porvoo to Oldenzaal | 903.23 mi (1,453.60 km) |
| Porvoo to Ommen | 908.90 mi (1,462.73 km) |
| Porvoo to Oosterend | 896.44 mi (1,442.69 km) |
| Porvoo to Oosterhout | 998.42 mi (1,606.81 km) |
| Porvoo to Oosterwolde | 890.17 mi (1,432.60 km) |
| Porvoo to Oostzaan | 959.55 mi (1,544.24 km) |
| Porvoo to Opmeer | 944.99 mi (1,520.81 km) |
| Porvoo to Oss | 972.52 mi (1,565.12 km) |
| Porvoo to Oud-Beijerland | 1,003.82 mi (1,615.49 km) |
| Porvoo to Oudenbosch | 1,011.13 mi (1,627.26 km) |
| Porvoo to Oudewater | 979.94 mi (1,577.06 km) |
