| Constanta to Oerlinghausen | 1,062.73 mi (1,710.30 km) |
| Constanta to Oestrich-Winkel | 1,046.75 mi (1,684.58 km) |
| Constanta to Offenburg | 1,027.87 mi (1,654.20 km) |
| Constanta to Oftersheim | 1,010.89 mi (1,626.87 km) |
| Constanta to Ohrdruf | 950.47 mi (1,529.64 km) |
| Constanta to Ohringen | 968.03 mi (1,557.89 km) |
| Constanta to Olbernhau | 842.16 mi (1,355.32 km) |
| Constanta to Olching | 871.74 mi (1,402.93 km) |
| Constanta to Oldenburg | 1,113.31 mi (1,791.71 km) |
| Constanta to Oldenburg in Holstein | 1,058.37 mi (1,703.28 km) |
| Constanta to Olfen | 1,107.61 mi (1,782.53 km) |
| Constanta to Olpe | 1,073.60 mi (1,727.79 km) |
| Constanta to Olsberg | 1,054.53 mi (1,697.10 km) |
| Constanta to Oranienburg | 918.44 mi (1,478.09 km) |
| Constanta to Ortenberg | 1,008.71 mi (1,623.36 km) |
