| Harrow on the Hill to Opwijk | 199.54 mi (321.12 km) |
| Harrow on the Hill to Ostend | 142.14 mi (228.75 km) |
| Harrow on the Hill to Oud-Heverlee | 222.23 mi (357.65 km) |
| Harrow on the Hill to Oud-Turnhout | 229.54 mi (369.41 km) |
| Harrow on the Hill to Oudenaarde | 177.24 mi (285.24 km) |
| Harrow on the Hill to Oudenburg | 146.13 mi (235.18 km) |
| Harrow on the Hill to Oupeye | 265.67 mi (427.56 km) |
| Harrow on the Hill to Overijse | 217.56 mi (350.13 km) |
| Harrow on the Hill to Overpelt | 248.98 mi (400.70 km) |
| Harrow on the Hill to Paal | 240.53 mi (387.10 km) |
| Harrow on the Hill to Peer | 251.42 mi (404.62 km) |
| Harrow on the Hill to Pepinster | 275.69 mi (443.67 km) |
| Harrow on the Hill to Peruwelz | 184.88 mi (297.54 km) |
| Harrow on the Hill to Perwez | 232.59 mi (374.32 km) |
| Harrow on the Hill to Philippeville | 232.76 mi (374.59 km) |
