| Slough to Mangualde | 827.23 mi (1,331.30 km) |
| Slough to Marco de Canavezes | 798.37 mi (1,284.86 km) |
| Slough to Marinha Grande | 905.60 mi (1,457.42 km) |
| Slough to Massama | 975.89 mi (1,570.55 km) |
| Slough to Matosinhos | 810.40 mi (1,304.21 km) |
| Slough to Mealhada | 855.29 mi (1,376.45 km) |
| Slough to Melgaco | 742.63 mi (1,195.16 km) |
| Slough to Melres | 811.08 mi (1,305.30 km) |
| Slough to Mira | 858.14 mi (1,381.04 km) |
| Slough to Miranda do Corvo | 870.90 mi (1,401.58 km) |
| Slough to Mirandela | 759.48 mi (1,222.26 km) |
| Slough to Mogadouro | 760.56 mi (1,224.00 km) |
| Slough to Moimenta da Beira | 800.29 mi (1,287.95 km) |
| Slough to Moita | 976.77 mi (1,571.96 km) |
| Slough to Moncao | 750.23 mi (1,207.38 km) |
