| Caerfyrddin to Oerlinghausen | 552.67 mi (889.44 km) |
| Caerfyrddin to Oestrich-Winkel | 550.74 mi (886.33 km) |
| Caerfyrddin to Offenburg | 589.66 mi (948.96 km) |
| Caerfyrddin to Oftersheim | 590.19 mi (949.81 km) |
| Caerfyrddin to Ohrdruf | 652.20 mi (1,049.62 km) |
| Caerfyrddin to Ohringen | 632.85 mi (1,018.48 km) |
| Caerfyrddin to Olbernhau | 765.60 mi (1,232.11 km) |
| Caerfyrddin to Olching | 736.66 mi (1,185.53 km) |
| Caerfyrddin to Oldenburg | 533.77 mi (859.01 km) |
| Caerfyrddin to Oldenburg in Holstein | 651.64 mi (1,048.71 km) |
| Caerfyrddin to Olfen | 499.59 mi (804.02 km) |
| Caerfyrddin to Olpe | 525.87 mi (846.31 km) |
| Caerfyrddin to Olsberg | 549.67 mi (884.61 km) |
| Caerfyrddin to Oranienburg | 742.30 mi (1,194.61 km) |
| Caerfyrddin to Ortenberg | 588.39 mi (946.92 km) |
