| Seia to Mangualde | 12.96 mi (20.86 km) |
| Seia to Marco de Canavezes | 57.57 mi (92.66 km) |
| Seia to Marinha Grande | 79.93 mi (128.64 km) |
| Seia to Massama | 142.29 mi (228.99 km) |
| Seia to Matosinhos | 74.09 mi (119.23 km) |
| Seia to Mealhada | 39.43 mi (63.45 km) |
| Seia to Melgaco | 120.70 mi (194.25 km) |
| Seia to Melres | 57.60 mi (92.70 km) |
| Seia to Mira | 54.23 mi (87.27 km) |
| Seia to Miranda do Corvo | 40.02 mi (64.40 km) |
| Seia to Mirandela | 78.33 mi (126.06 km) |
| Seia to Mogadouro | 81.34 mi (130.90 km) |
| Seia to Moimenta da Beira | 38.81 mi (62.46 km) |
| Seia to Moita | 140.17 mi (225.58 km) |
| Seia to Moncao | 121.03 mi (194.78 km) |
