| Grefrath to Smolyan | 1,098.29 mi (1,767.53 km) |
| Grefrath to Sofia | 994.28 mi (1,600.14 km) |
| Grefrath to Sopot | 1,050.24 mi (1,690.20 km) |
| Grefrath to Sozopol | 1,175.63 mi (1,891.99 km) |
| Grefrath to Sredets | 1,158.79 mi (1,864.89 km) |
| Grefrath to Stamboliyski | 1,065.92 mi (1,715.44 km) |
| Grefrath to Stara Zagora | 1,094.64 mi (1,761.65 km) |
| Grefrath to Svilengrad | 1,146.25 mi (1,844.71 km) |
| Grefrath to Svishtov | 1,031.10 mi (1,659.39 km) |
| Grefrath to Targovishte | 1,095.53 mi (1,763.09 km) |
| Grefrath to Teteven | 1,019.66 mi (1,640.98 km) |
| Grefrath to Troyan | 1,038.41 mi (1,671.16 km) |
| Grefrath to Tryavna | 1,069.45 mi (1,721.11 km) |
| Grefrath to Tutrakan | 1,063.96 mi (1,712.27 km) |
| Grefrath to Varna | 1,150.40 mi (1,851.39 km) |
