| Hertford to Smolyan | 1,359.98 mi (2,188.68 km) |
| Hertford to Sofia | 1,256.91 mi (2,022.80 km) |
| Hertford to Sopot | 1,316.11 mi (2,118.08 km) |
| Hertford to Sozopol | 1,446.15 mi (2,327.35 km) |
| Hertford to Sredets | 1,428.34 mi (2,298.70 km) |
| Hertford to Stamboliyski | 1,329.34 mi (2,139.37 km) |
| Hertford to Stara Zagora | 1,361.64 mi (2,191.35 km) |
| Hertford to Svilengrad | 1,412.15 mi (2,272.64 km) |
| Hertford to Svishtov | 1,301.36 mi (2,094.33 km) |
| Hertford to Targovishte | 1,366.63 mi (2,199.39 km) |
| Hertford to Teteven | 1,285.45 mi (2,068.73 km) |
| Hertford to Troyan | 1,305.06 mi (2,100.29 km) |
| Hertford to Tryavna | 1,337.59 mi (2,152.65 km) |
| Hertford to Tutrakan | 1,337.13 mi (2,151.90 km) |
| Hertford to Varna | 1,423.16 mi (2,290.36 km) |
