| Irmo to Orbetello | 4,791.59 mi (7,711.31 km) |
| Irmo to Oria | 5,146.45 mi (8,282.41 km) |
| Irmo to Oristano | 4,751.85 mi (7,647.36 km) |
| Irmo to Orta Nova | 5,030.89 mi (8,096.43 km) |
| Irmo to Orte | 4,843.65 mi (7,795.10 km) |
| Irmo to Ortona | 4,937.16 mi (7,945.59 km) |
| Irmo to Orvieto | 4,822.83 mi (7,761.60 km) |
| Irmo to Orzinuovi | 4,642.05 mi (7,470.66 km) |
| Irmo to Osimo | 4,858.46 mi (7,818.94 km) |
| Irmo to Ospitaletto | 4,643.42 mi (7,472.86 km) |
| Irmo to Ostuni | 5,135.72 mi (8,265.14 km) |
| Irmo to Ottaviano | 4,992.24 mi (8,034.24 km) |
| Irmo to Ovada | 4,608.42 mi (7,416.53 km) |
| Irmo to Ozieri | 4,749.60 mi (7,643.74 km) |
| Irmo to Paceco | 5,002.17 mi (8,050.21 km) |
