| Merthyr Tudful to Karlovo | 1,452.85 mi (2,338.14 km) |
| Merthyr Tudful to Karnobat | 1,543.88 mi (2,484.64 km) |
| Merthyr Tudful to Kavarna | 1,570.11 mi (2,526.84 km) |
| Merthyr Tudful to Kazanlak | 1,478.52 mi (2,379.45 km) |
| Merthyr Tudful to Knezha | 1,389.16 mi (2,235.64 km) |
| Merthyr Tudful to Kostinbrod | 1,380.24 mi (2,221.28 km) |
| Merthyr Tudful to Kozloduy | 1,363.76 mi (2,194.76 km) |
| Merthyr Tudful to Kyustendil | 1,380.34 mi (2,221.44 km) |
| Merthyr Tudful to Levski | 1,438.08 mi (2,314.36 km) |
| Merthyr Tudful to Lom | 1,341.51 mi (2,158.95 km) |
| Merthyr Tudful to Lovech | 1,429.70 mi (2,300.88 km) |
| Merthyr Tudful to Lukovit | 1,404.27 mi (2,259.95 km) |
| Merthyr Tudful to Lyaskovets | 1,472.73 mi (2,370.13 km) |
| Merthyr Tudful to Mezdra | 1,386.88 mi (2,231.97 km) |
| Merthyr Tudful to Momchilgrad | 1,523.54 mi (2,451.90 km) |
