| Grefrath to Orzesze | 548.03 mi (881.97 km) |
| Grefrath to Osowa | 548.10 mi (882.08 km) |
| Grefrath to Ostroda | 594.65 mi (957.00 km) |
| Grefrath to Ostroleka | 654.44 mi (1,053.22 km) |
| Grefrath to Ostrow Mazowiecka | 667.19 mi (1,073.73 km) |
| Grefrath to Ostrow Wielkopolski | 493.63 mi (794.41 km) |
| Grefrath to Ostrowiec Swietokrzyski | 652.34 mi (1,049.84 km) |
| Grefrath to Ostrzeszow | 499.47 mi (803.82 km) |
| Grefrath to Oswiecim | 570.16 mi (917.59 km) |
| Grefrath to Otwock | 639.92 mi (1,029.86 km) |
| Grefrath to Ozarow Mazowiecki | 620.07 mi (997.91 km) |
| Grefrath to Ozimek | 517.63 mi (833.05 km) |
| Grefrath to Ozorkow | 555.79 mi (894.46 km) |
| Grefrath to Pabianice | 560.74 mi (902.42 km) |
| Grefrath to Parczew | 709.82 mi (1,142.35 km) |
