| Porsgrunn to Oerlinghausen | 495.61 mi (797.60 km) |
| Porsgrunn to Oestrich-Winkel | 633.49 mi (1,019.50 km) |
| Porsgrunn to Offenburg | 739.26 mi (1,189.73 km) |
| Porsgrunn to Oftersheim | 674.82 mi (1,086.02 km) |
| Porsgrunn to Ohrdruf | 574.03 mi (923.81 km) |
| Porsgrunn to Ohringen | 685.15 mi (1,102.65 km) |
| Porsgrunn to Olbernhau | 601.03 mi (967.27 km) |
| Porsgrunn to Olching | 757.00 mi (1,218.28 km) |
| Porsgrunn to Oldenburg | 416.58 mi (670.42 km) |
| Porsgrunn to Oldenburg in Holstein | 335.67 mi (540.22 km) |
| Porsgrunn to Olfen | 519.21 mi (835.59 km) |
| Porsgrunn to Olpe | 564.43 mi (908.36 km) |
| Porsgrunn to Olsberg | 538.70 mi (866.95 km) |
| Porsgrunn to Oranienburg | 460.06 mi (740.40 km) |
| Porsgrunn to Ortenberg | 605.80 mi (974.94 km) |
