| Houghton Regis to Smolyan | 1,380.46 mi (2,221.64 km) |
| Houghton Regis to Sofia | 1,277.39 mi (2,055.76 km) |
| Houghton Regis to Sopot | 1,336.57 mi (2,151.01 km) |
| Houghton Regis to Sozopol | 1,466.52 mi (2,360.14 km) |
| Houghton Regis to Sredets | 1,448.75 mi (2,331.53 km) |
| Houghton Regis to Stamboliyski | 1,349.82 mi (2,172.32 km) |
| Houghton Regis to Stara Zagora | 1,382.09 mi (2,224.26 km) |
| Houghton Regis to Svilengrad | 1,432.61 mi (2,305.57 km) |
| Houghton Regis to Svishtov | 1,321.74 mi (2,127.13 km) |
| Houghton Regis to Targovishte | 1,386.99 mi (2,232.14 km) |
| Houghton Regis to Teteven | 1,305.91 mi (2,101.66 km) |
| Houghton Regis to Troyan | 1,325.51 mi (2,133.20 km) |
| Houghton Regis to Tryavna | 1,358.02 mi (2,185.53 km) |
| Houghton Regis to Tutrakan | 1,357.39 mi (2,184.51 km) |
| Houghton Regis to Varna | 1,443.45 mi (2,323.01 km) |
