| Harrow to Smolyan | 1,365.47 mi (2,197.51 km) |
| Harrow to Sofia | 1,262.63 mi (2,032.00 km) |
| Harrow to Sopot | 1,322.40 mi (2,128.20 km) |
| Harrow to Sozopol | 1,453.41 mi (2,339.04 km) |
| Harrow to Sredets | 1,435.38 mi (2,310.02 km) |
| Harrow to Stamboliyski | 1,335.15 mi (2,148.72 km) |
| Harrow to Stara Zagora | 1,368.14 mi (2,201.81 km) |
| Harrow to Svilengrad | 1,418.40 mi (2,282.69 km) |
| Harrow to Svishtov | 1,308.62 mi (2,106.02 km) |
| Harrow to Targovishte | 1,374.08 mi (2,211.37 km) |
| Harrow to Teteven | 1,291.74 mi (2,078.86 km) |
| Harrow to Troyan | 1,311.51 mi (2,110.67 km) |
| Harrow to Tryavna | 1,344.35 mi (2,163.52 km) |
| Harrow to Tutrakan | 1,345.18 mi (2,164.85 km) |
| Harrow to Varna | 1,431.05 mi (2,303.06 km) |
