| Monmouth to Smolyan | 1,466.60 mi (2,360.26 km) |
| Monmouth to Sofia | 1,364.00 mi (2,195.15 km) |
| Monmouth to Sopot | 1,424.26 mi (2,292.12 km) |
| Monmouth to Sozopol | 1,555.88 mi (2,503.95 km) |
| Monmouth to Sredets | 1,537.73 mi (2,474.73 km) |
| Monmouth to Stamboliyski | 1,436.60 mi (2,311.99 km) |
| Monmouth to Stara Zagora | 1,470.14 mi (2,365.97 km) |
| Monmouth to Svilengrad | 1,520.21 mi (2,446.53 km) |
| Monmouth to Svishtov | 1,411.09 mi (2,270.93 km) |
| Monmouth to Targovishte | 1,476.63 mi (2,376.41 km) |
| Monmouth to Teteven | 1,393.60 mi (2,242.78 km) |
| Monmouth to Troyan | 1,413.49 mi (2,274.79 km) |
| Monmouth to Tryavna | 1,446.53 mi (2,327.97 km) |
| Monmouth to Tutrakan | 1,447.93 mi (2,330.22 km) |
| Monmouth to Varna | 1,533.77 mi (2,468.36 km) |
