| Dayton to Oerlinghausen | 4,235.09 mi (6,815.73 km) |
| Dayton to Oestrich-Winkel | 4,276.09 mi (6,881.70 km) |
| Dayton to Offenburg | 4,326.13 mi (6,962.23 km) |
| Dayton to Oftersheim | 4,320.38 mi (6,952.98 km) |
| Dayton to Ohrdruf | 4,351.49 mi (7,003.05 km) |
| Dayton to Ohringen | 4,361.92 mi (7,019.83 km) |
| Dayton to Olbernhau | 4,454.19 mi (7,168.32 km) |
| Dayton to Olching | 4,468.64 mi (7,191.58 km) |
| Dayton to Oldenburg | 4,179.55 mi (6,726.34 km) |
| Dayton to Oldenburg in Holstein | 4,237.00 mi (6,818.79 km) |
| Dayton to Olfen | 4,195.27 mi (6,751.63 km) |
| Dayton to Olpe | 4,235.45 mi (6,816.30 km) |
| Dayton to Olsberg | 4,248.90 mi (6,837.95 km) |
| Dayton to Oranienburg | 4,374.38 mi (7,039.88 km) |
| Dayton to Ortenberg | 4,304.47 mi (6,927.38 km) |
