| Merthyr Tudful to Popovo | 1,484.77 mi (2,389.51 km) |
| Merthyr Tudful to Provadia | 1,541.54 mi (2,480.87 km) |
| Merthyr Tudful to Radnevo | 1,513.35 mi (2,435.51 km) |
| Merthyr Tudful to Radomir | 1,380.17 mi (2,221.16 km) |
| Merthyr Tudful to Rakitovo | 1,450.02 mi (2,333.58 km) |
| Merthyr Tudful to Rakovski | 1,473.74 mi (2,371.75 km) |
| Merthyr Tudful to Razgrad | 1,489.76 mi (2,397.54 km) |
| Merthyr Tudful to Razlog | 1,429.04 mi (2,299.81 km) |
| Merthyr Tudful to Ruse | 1,455.28 mi (2,342.04 km) |
| Merthyr Tudful to Samokov | 1,413.72 mi (2,275.16 km) |
| Merthyr Tudful to Sandanski | 1,434.97 mi (2,309.35 km) |
| Merthyr Tudful to Sevlievo | 1,450.45 mi (2,334.28 km) |
| Merthyr Tudful to Shumen | 1,516.71 mi (2,440.91 km) |
| Merthyr Tudful to Silistra | 1,499.68 mi (2,413.50 km) |
| Merthyr Tudful to Sliven | 1,514.75 mi (2,437.75 km) |
