| Porsgrunn to Opwijk | 603.56 mi (971.33 km) |
| Porsgrunn to Ostend | 606.71 mi (976.41 km) |
| Porsgrunn to Oud-Heverlee | 605.77 mi (974.89 km) |
| Porsgrunn to Oud-Turnhout | 569.80 mi (917.00 km) |
| Porsgrunn to Oudenaarde | 619.74 mi (997.37 km) |
| Porsgrunn to Oudenburg | 608.03 mi (978.54 km) |
| Porsgrunn to Oupeye | 602.65 mi (969.87 km) |
| Porsgrunn to Overijse | 610.81 mi (983.00 km) |
| Porsgrunn to Overpelt | 571.16 mi (919.20 km) |
| Porsgrunn to Paal | 585.84 mi (942.81 km) |
| Porsgrunn to Peer | 576.33 mi (927.51 km) |
| Porsgrunn to Pepinster | 610.38 mi (982.32 km) |
| Porsgrunn to Peruwelz | 641.60 mi (1,032.56 km) |
| Porsgrunn to Perwez | 617.73 mi (994.15 km) |
| Porsgrunn to Philippeville | 649.14 mi (1,044.69 km) |
