| Harpenden to Mangualde | 850.84 mi (1,369.30 km) |
| Harpenden to Marco de Canavezes | 821.93 mi (1,322.77 km) |
| Harpenden to Marinha Grande | 929.16 mi (1,495.34 km) |
| Harpenden to Massama | 999.47 mi (1,608.50 km) |
| Harpenden to Matosinhos | 833.89 mi (1,342.01 km) |
| Harpenden to Mealhada | 878.86 mi (1,414.39 km) |
| Harpenden to Melgaco | 766.09 mi (1,232.91 km) |
| Harpenden to Melres | 834.62 mi (1,343.18 km) |
| Harpenden to Mira | 881.68 mi (1,418.93 km) |
| Harpenden to Miranda do Corvo | 894.49 mi (1,439.55 km) |
| Harpenden to Mirandela | 783.09 mi (1,260.27 km) |
| Harpenden to Mogadouro | 784.18 mi (1,262.02 km) |
| Harpenden to Moimenta da Beira | 823.90 mi (1,325.94 km) |
| Harpenden to Moita | 1,000.37 mi (1,609.95 km) |
| Harpenden to Moncao | 773.66 mi (1,245.08 km) |
