| Caerphilly to Oerlinghausen | 508.26 mi (817.97 km) |
| Caerphilly to Oestrich-Winkel | 501.44 mi (806.98 km) |
| Caerphilly to Offenburg | 538.97 mi (867.39 km) |
| Caerphilly to Oftersheim | 540.25 mi (869.45 km) |
| Caerphilly to Ohrdruf | 605.24 mi (974.04 km) |
| Caerphilly to Ohringen | 582.98 mi (938.22 km) |
| Caerphilly to Olbernhau | 718.98 mi (1,157.09 km) |
| Caerphilly to Olching | 686.40 mi (1,104.66 km) |
| Caerphilly to Oldenburg | 493.77 mi (794.64 km) |
| Caerphilly to Oldenburg in Holstein | 615.33 mi (990.29 km) |
| Caerphilly to Olfen | 454.20 mi (730.97 km) |
| Caerphilly to Olpe | 478.56 mi (770.16 km) |
| Caerphilly to Olsberg | 503.40 mi (810.14 km) |
| Caerphilly to Oranienburg | 700.52 mi (1,127.37 km) |
| Caerphilly to Ortenberg | 540.02 mi (869.07 km) |
