| Karlovo to Opwijk | 1,126.59 mi (1,813.07 km) |
| Karlovo to Ostend | 1,184.14 mi (1,905.69 km) |
| Karlovo to Oud-Heverlee | 1,103.60 mi (1,776.07 km) |
| Karlovo to Oud-Turnhout | 1,104.66 mi (1,777.78 km) |
| Karlovo to Oudenaarde | 1,147.13 mi (1,846.13 km) |
| Karlovo to Oudenburg | 1,179.82 mi (1,898.73 km) |
| Karlovo to Oupeye | 1,061.05 mi (1,707.59 km) |
| Karlovo to Overijse | 1,107.63 mi (1,782.55 km) |
| Karlovo to Overpelt | 1,084.77 mi (1,745.76 km) |
| Karlovo to Paal | 1,089.16 mi (1,752.84 km) |
| Karlovo to Peer | 1,080.84 mi (1,739.44 km) |
| Karlovo to Pepinster | 1,050.10 mi (1,689.98 km) |
| Karlovo to Peruwelz | 1,139.62 mi (1,834.05 km) |
| Karlovo to Perwez | 1,092.02 mi (1,757.44 km) |
| Karlovo to Philippeville | 1,092.04 mi (1,757.47 km) |
