| Clay to Opwijk | 4,486.38 mi (7,220.12 km) |
| Clay to Ostend | 4,428.88 mi (7,127.60 km) |
| Clay to Oud-Heverlee | 4,509.37 mi (7,257.13 km) |
| Clay to Oud-Turnhout | 4,508.54 mi (7,255.80 km) |
| Clay to Oudenaarde | 4,466.17 mi (7,187.61 km) |
| Clay to Oudenburg | 4,433.23 mi (7,134.59 km) |
| Clay to Oupeye | 4,551.85 mi (7,325.50 km) |
| Clay to Overijse | 4,505.42 mi (7,250.77 km) |
| Clay to Overpelt | 4,528.47 mi (7,287.87 km) |
| Clay to Paal | 4,523.79 mi (7,280.34 km) |
| Clay to Peer | 4,532.29 mi (7,294.02 km) |
| Clay to Pepinster | 4,562.83 mi (7,343.16 km) |
| Clay to Peruwelz | 4,474.51 mi (7,201.03 km) |
| Clay to Perwez | 4,521.13 mi (7,276.06 km) |
| Clay to Philippeville | 4,522.31 mi (7,277.96 km) |
