| Boulogne-sur-Mer to Opwijk | 113.27 mi (182.30 km) |
| Boulogne-sur-Mer to Ostend | 66.42 mi (106.90 km) |
| Boulogne-sur-Mer to Oud-Heverlee | 133.53 mi (214.90 km) |
| Boulogne-sur-Mer to Oud-Turnhout | 151.96 mi (244.56 km) |
| Boulogne-sur-Mer to Oudenaarde | 87.13 mi (140.23 km) |
| Boulogne-sur-Mer to Oudenburg | 68.06 mi (109.53 km) |
| Boulogne-sur-Mer to Oupeye | 176.21 mi (283.58 km) |
| Boulogne-sur-Mer to Overijse | 127.63 mi (205.40 km) |
| Boulogne-sur-Mer to Overpelt | 168.83 mi (271.71 km) |
| Boulogne-sur-Mer to Paal | 156.59 mi (252.00 km) |
| Boulogne-sur-Mer to Peer | 169.50 mi (272.78 km) |
| Boulogne-sur-Mer to Pepinster | 184.40 mi (296.77 km) |
| Boulogne-sur-Mer to Peruwelz | 87.50 mi (140.82 km) |
| Boulogne-sur-Mer to Perwez | 140.29 mi (225.78 km) |
| Boulogne-sur-Mer to Philippeville | 134.12 mi (215.84 km) |
