| Letchworth to Smolyan | 1,370.64 mi (2,205.84 km) |
| Letchworth to Sofia | 1,267.46 mi (2,039.78 km) |
| Letchworth to Sopot | 1,326.35 mi (2,134.55 km) |
| Letchworth to Sozopol | 1,455.81 mi (2,342.90 km) |
| Letchworth to Sredets | 1,438.15 mi (2,314.47 km) |
| Letchworth to Stamboliyski | 1,339.83 mi (2,156.25 km) |
| Letchworth to Stara Zagora | 1,371.76 mi (2,207.63 km) |
| Letchworth to Svilengrad | 1,422.40 mi (2,289.14 km) |
| Letchworth to Svishtov | 1,311.04 mi (2,109.91 km) |
| Letchworth to Targovishte | 1,376.20 mi (2,214.77 km) |
| Letchworth to Teteven | 1,295.69 mi (2,085.21 km) |
| Letchworth to Troyan | 1,315.20 mi (2,116.62 km) |
| Letchworth to Tryavna | 1,347.57 mi (2,168.70 km) |
| Letchworth to Tutrakan | 1,346.32 mi (2,166.70 km) |
| Letchworth to Varna | 1,432.44 mi (2,305.30 km) |
