| Potters Bar to Mangualde | 846.91 mi (1,362.97 km) |
| Potters Bar to Marco de Canavezes | 818.42 mi (1,317.13 km) |
| Potters Bar to Marinha Grande | 925.62 mi (1,489.64 km) |
| Potters Bar to Massama | 995.82 mi (1,602.62 km) |
| Potters Bar to Matosinhos | 830.71 mi (1,336.90 km) |
| Potters Bar to Mealhada | 875.25 mi (1,408.58 km) |
| Potters Bar to Melgaco | 763.03 mi (1,227.98 km) |
| Potters Bar to Melres | 831.22 mi (1,337.71 km) |
| Potters Bar to Mira | 878.25 mi (1,413.41 km) |
| Potters Bar to Miranda do Corvo | 890.73 mi (1,433.49 km) |
| Potters Bar to Mirandela | 779.10 mi (1,253.83 km) |
| Potters Bar to Mogadouro | 779.84 mi (1,255.03 km) |
| Potters Bar to Moimenta da Beira | 820.00 mi (1,319.66 km) |
| Potters Bar to Moita | 996.54 mi (1,603.78 km) |
| Potters Bar to Moncao | 770.71 mi (1,240.34 km) |
