| Chelmsford to Orbetello | 814.93 mi (1,311.50 km) |
| Chelmsford to Oria | 1,124.83 mi (1,810.23 km) |
| Chelmsford to Oristano | 904.22 mi (1,455.21 km) |
| Chelmsford to Orta Nova | 1,016.16 mi (1,635.35 km) |
| Chelmsford to Orte | 848.63 mi (1,365.74 km) |
| Chelmsford to Ortona | 918.81 mi (1,478.68 km) |
| Chelmsford to Orvieto | 825.95 mi (1,329.24 km) |
| Chelmsford to Orzinuovi | 613.97 mi (988.09 km) |
| Chelmsford to Osimo | 829.34 mi (1,334.70 km) |
| Chelmsford to Ospitaletto | 610.47 mi (982.46 km) |
| Chelmsford to Ostuni | 1,110.92 mi (1,787.86 km) |
| Chelmsford to Ottaviano | 1,002.40 mi (1,613.21 km) |
| Chelmsford to Ovada | 616.90 mi (992.80 km) |
| Chelmsford to Ozieri | 870.05 mi (1,400.21 km) |
| Chelmsford to Paceco | 1,115.48 mi (1,795.19 km) |
