| Rhondda to Oerlinghausen | 516.40 mi (831.07 km) |
| Rhondda to Oestrich-Winkel | 510.28 mi (821.22 km) |
| Rhondda to Offenburg | 547.92 mi (881.79 km) |
| Rhondda to Oftersheim | 549.17 mi (883.80 km) |
| Rhondda to Ohrdruf | 613.78 mi (987.78 km) |
| Rhondda to Ohringen | 591.89 mi (952.56 km) |
| Rhondda to Olbernhau | 727.48 mi (1,170.76 km) |
| Rhondda to Olching | 695.34 mi (1,119.05 km) |
| Rhondda to Oldenburg | 501.20 mi (806.60 km) |
| Rhondda to Oldenburg in Holstein | 622.18 mi (1,001.30 km) |
| Rhondda to Olfen | 462.49 mi (744.31 km) |
| Rhondda to Olpe | 487.14 mi (783.97 km) |
| Rhondda to Olsberg | 511.83 mi (823.71 km) |
| Rhondda to Oranienburg | 708.27 mi (1,139.85 km) |
| Rhondda to Ortenberg | 548.75 mi (883.12 km) |
