| Guastalla to Smolyan | 741.70 mi (1,193.66 km) |
| Guastalla to Sofia | 648.98 mi (1,044.43 km) |
| Guastalla to Sopot | 718.76 mi (1,156.74 km) |
| Guastalla to Sozopol | 866.95 mi (1,395.22 km) |
| Guastalla to Sredets | 844.00 mi (1,358.29 km) |
| Guastalla to Stamboliyski | 719.79 mi (1,158.39 km) |
| Guastalla to Stara Zagora | 766.96 mi (1,234.30 km) |
| Guastalla to Svilengrad | 808.88 mi (1,301.77 km) |
| Guastalla to Svishtov | 731.00 mi (1,176.43 km) |
| Guastalla to Targovishte | 796.99 mi (1,282.63 km) |
| Guastalla to Teteven | 689.97 mi (1,110.40 km) |
| Guastalla to Troyan | 712.49 mi (1,146.64 km) |
| Guastalla to Tryavna | 750.91 mi (1,208.48 km) |
| Guastalla to Tutrakan | 787.25 mi (1,266.96 km) |
| Guastalla to Varna | 862.73 mi (1,388.43 km) |
