| Middlesbrough to Mangualde | 1,011.09 mi (1,627.19 km) |
| Middlesbrough to Marco de Canavezes | 978.14 mi (1,574.17 km) |
| Middlesbrough to Marinha Grande | 1,084.81 mi (1,745.84 km) |
| Middlesbrough to Massama | 1,155.80 mi (1,860.08 km) |
| Middlesbrough to Matosinhos | 986.59 mi (1,587.76 km) |
| Middlesbrough to Mealhada | 1,035.60 mi (1,666.63 km) |
| Middlesbrough to Melgaco | 918.34 mi (1,477.93 km) |
| Middlesbrough to Melres | 989.61 mi (1,592.63 km) |
| Middlesbrough to Mira | 1,036.56 mi (1,668.19 km) |
| Middlesbrough to Miranda do Corvo | 1,052.70 mi (1,694.16 km) |
| Middlesbrough to Mirandela | 944.49 mi (1,520.01 km) |
| Middlesbrough to Mogadouro | 948.81 mi (1,526.96 km) |
| Middlesbrough to Moimenta da Beira | 984.03 mi (1,583.65 km) |
| Middlesbrough to Moita | 1,158.55 mi (1,864.51 km) |
| Middlesbrough to Moncao | 924.61 mi (1,488.01 km) |
