| Portsmouth to Mangualde | 774.17 mi (1,245.90 km) |
| Portsmouth to Marco de Canavezes | 745.48 mi (1,199.74 km) |
| Portsmouth to Marinha Grande | 852.69 mi (1,372.27 km) |
| Portsmouth to Massama | 922.93 mi (1,485.32 km) |
| Portsmouth to Matosinhos | 757.71 mi (1,219.42 km) |
| Portsmouth to Mealhada | 802.35 mi (1,291.25 km) |
| Portsmouth to Melgaco | 690.03 mi (1,110.50 km) |
| Portsmouth to Melres | 758.25 mi (1,220.28 km) |
| Portsmouth to Mira | 805.29 mi (1,296.00 km) |
| Portsmouth to Miranda do Corvo | 817.89 mi (1,316.27 km) |
| Portsmouth to Mirandela | 706.39 mi (1,136.83 km) |
| Portsmouth to Mogadouro | 707.42 mi (1,138.48 km) |
| Portsmouth to Moimenta da Beira | 747.24 mi (1,202.56 km) |
| Portsmouth to Moita | 923.74 mi (1,486.62 km) |
| Portsmouth to Moncao | 697.72 mi (1,122.87 km) |
