| Statistic | Montmagny | Quebec | National |
| Population | 10,961 | 8,565,732 | 38,134,230 |
| Population density (sq km) | 89 | 6 | 4 |
| Median age | 52.6 | 42.6 | 40.9 |
| Male/Female ratio | 1.1:1 | 1.0:1 | 1.0:1 |
| Married couples | 48% | 50% | 66% |
| Families w/ kids at home | 34% | 40% | 43% |
| Speak English only | 0.1% | 4.7% | 68.8% |
| Speak French only | 81.0% | 49.5% | 4.5% |
| Data | Percent |
| Black | 0.6% |
| Latin American | 0.4% |
| Arab | 0.2% |
| Chinese | 0.2% |
| Filipino | 0.1% |
| Data | Percent |
| France | 0.3% |
| Haiti | 0.2% |
| Morocco | 0.2% |
| China | 0.1% |
| United States | 0.1% |