| Watford to Karlovo | 1,328.53 mi (2,138.07 km) |
| Watford to Karnobat | 1,418.34 mi (2,282.59 km) |
| Watford to Kavarna | 1,443.38 mi (2,322.89 km) |
| Watford to Kazanlak | 1,353.85 mi (2,178.82 km) |
| Watford to Knezha | 1,264.26 mi (2,034.63 km) |
| Watford to Kostinbrod | 1,256.83 mi (2,022.67 km) |
| Watford to Kozloduy | 1,238.72 mi (1,993.53 km) |
| Watford to Kyustendil | 1,258.18 mi (2,024.85 km) |
| Watford to Levski | 1,312.73 mi (2,112.64 km) |
| Watford to Lom | 1,216.71 mi (1,958.11 km) |
| Watford to Lovech | 1,304.85 mi (2,099.96 km) |
| Watford to Lukovit | 1,279.68 mi (2,059.44 km) |
| Watford to Lyaskovets | 1,347.36 mi (2,168.37 km) |
| Watford to Mezdra | 1,262.66 mi (2,032.06 km) |
| Watford to Momchilgrad | 1,400.18 mi (2,253.38 km) |
