| Gloucester to Oberkirch | 510.85 mi (822.14 km) |
| Gloucester to Obernburg am Main | 515.36 mi (829.39 km) |
| Gloucester to Obernkirchen | 482.92 mi (777.19 km) |
| Gloucester to Oberschleissheim | 660.29 mi (1,062.63 km) |
| Gloucester to Oberstdorf | 638.15 mi (1,027.00 km) |
| Gloucester to Obertraubling | 664.06 mi (1,068.70 km) |
| Gloucester to Obertshausen | 497.24 mi (800.22 km) |
| Gloucester to Oberursel | 483.49 mi (778.10 km) |
| Gloucester to Ochsenfurt | 558.66 mi (899.07 km) |
| Gloucester to Ochsenhausen | 600.87 mi (967.01 km) |
| Gloucester to Ochtrup | 401.43 mi (646.04 km) |
| Gloucester to Odenthal | 406.87 mi (654.79 km) |
| Gloucester to Oelde | 443.28 mi (713.39 km) |
| Gloucester to Oelsnitz | 631.60 mi (1,016.46 km) |
| Gloucester to Oer-Erkenschwick | 406.13 mi (653.61 km) |
