| Northolt to Smolyan | 1,365.53 mi (2,197.60 km) |
| Northolt to Sofia | 1,262.72 mi (2,032.16 km) |
| Northolt to Sopot | 1,322.58 mi (2,128.49 km) |
| Northolt to Sozopol | 1,453.75 mi (2,339.58 km) |
| Northolt to Sredets | 1,435.68 mi (2,310.50 km) |
| Northolt to Stamboliyski | 1,335.26 mi (2,148.90 km) |
| Northolt to Stara Zagora | 1,368.35 mi (2,202.15 km) |
| Northolt to Svilengrad | 1,418.57 mi (2,282.97 km) |
| Northolt to Svishtov | 1,308.96 mi (2,106.56 km) |
| Northolt to Targovishte | 1,374.44 mi (2,211.95 km) |
| Northolt to Teteven | 1,291.92 mi (2,079.15 km) |
| Northolt to Troyan | 1,311.72 mi (2,111.01 km) |
| Northolt to Tryavna | 1,344.60 mi (2,163.93 km) |
| Northolt to Tutrakan | 1,345.64 mi (2,165.59 km) |
| Northolt to Varna | 1,431.49 mi (2,303.76 km) |
