| Helensburgh to Oerlinghausen | 610.63 mi (982.71 km) |
| Helensburgh to Oestrich-Winkel | 671.33 mi (1,080.40 km) |
| Helensburgh to Offenburg | 745.71 mi (1,200.10 km) |
| Helensburgh to Oftersheim | 720.32 mi (1,159.24 km) |
| Helensburgh to Ohrdruf | 728.46 mi (1,172.34 km) |
| Helensburgh to Ohringen | 758.11 mi (1,220.06 km) |
| Helensburgh to Olbernhau | 828.57 mi (1,333.45 km) |
| Helensburgh to Olching | 865.67 mi (1,393.16 km) |
| Helensburgh to Oldenburg | 554.11 mi (891.76 km) |
| Helensburgh to Oldenburg in Holstein | 626.33 mi (1,007.97 km) |
| Helensburgh to Olfen | 574.99 mi (925.35 km) |
| Helensburgh to Olpe | 619.74 mi (997.38 km) |
| Helensburgh to Olsberg | 628.14 mi (1,010.89 km) |
| Helensburgh to Oranienburg | 754.84 mi (1,214.79 km) |
| Helensburgh to Ortenberg | 690.06 mi (1,110.54 km) |
