| Watford to Isny im Allgau | 540.26 mi (869.47 km) |
| Watford to Isselburg | 293.73 mi (472.71 km) |
| Watford to Issum | 292.69 mi (471.04 km) |
| Watford to Itzehoe | 442.40 mi (711.97 km) |
| Watford to Jena | 519.56 mi (836.15 km) |
| Watford to Jever | 372.19 mi (598.98 km) |
| Watford to Jork | 442.00 mi (711.33 km) |
| Watford to Juchen | 299.80 mi (482.48 km) |
| Watford to Julich | 296.09 mi (476.52 km) |
| Watford to Juterbog | 574.82 mi (925.09 km) |
| Watford to Kaarst | 303.43 mi (488.33 km) |
| Watford to Kaiserslautern | 389.34 mi (626.59 km) |
| Watford to Kalkar | 286.38 mi (460.89 km) |
| Watford to Kall | 310.72 mi (500.06 km) |
| Watford to Kaltenkirchen | 458.18 mi (737.36 km) |
