| Friendswood to Popovo | 6,186.20 mi (9,955.73 km) |
| Friendswood to Provadia | 6,238.52 mi (10,039.92 km) |
| Friendswood to Radnevo | 6,223.39 mi (10,015.57 km) |
| Friendswood to Radomir | 6,097.00 mi (9,812.17 km) |
| Friendswood to Rakitovo | 6,166.53 mi (9,924.06 km) |
| Friendswood to Rakovski | 6,186.89 mi (9,956.83 km) |
| Friendswood to Razgrad | 6,188.24 mi (9,959.01 km) |
| Friendswood to Razlog | 6,146.87 mi (9,892.44 km) |
| Friendswood to Ruse | 6,153.95 mi (9,903.82 km) |
| Friendswood to Samokov | 6,130.09 mi (9,865.43 km) |
| Friendswood to Sandanski | 6,153.65 mi (9,903.34 km) |
| Friendswood to Sevlievo | 6,158.95 mi (9,911.88 km) |
| Friendswood to Shumen | 6,215.33 mi (10,002.61 km) |
| Friendswood to Silistra | 6,188.33 mi (9,959.16 km) |
| Friendswood to Sliven | 6,220.82 mi (10,011.44 km) |
