| Round Rock to Smolyan | 6,249.17 mi (10,057.07 km) |
| Round Rock to Sofia | 6,145.24 mi (9,889.81 km) |
| Round Rock to Sopot | 6,200.46 mi (9,978.67 km) |
| Round Rock to Sozopol | 6,319.12 mi (10,169.64 km) |
| Round Rock to Sredets | 6,304.40 mi (10,145.96 km) |
| Round Rock to Stamboliyski | 6,216.88 mi (10,005.10 km) |
| Round Rock to Stara Zagora | 6,243.94 mi (10,048.65 km) |
| Round Rock to Svilengrad | 6,296.25 mi (10,132.84 km) |
| Round Rock to Svishtov | 6,176.36 mi (9,939.90 km) |
| Round Rock to Targovishte | 6,238.40 mi (10,039.73 km) |
| Round Rock to Teteven | 6,169.98 mi (9,929.62 km) |
| Round Rock to Troyan | 6,188.17 mi (9,958.89 km) |
| Round Rock to Tryavna | 6,217.67 mi (10,006.38 km) |
| Round Rock to Tutrakan | 6,200.77 mi (9,979.18 km) |
| Round Rock to Varna | 6,287.44 mi (10,118.66 km) |
