| Statistic | Saint-Guillaume | Quebec | National |
| Population | 1,444 | 8,565,732 | 38,134,230 |
| Population density (sq km) | 17 | 6 | 4 |
| Median age | 44.5 | 42.6 | 40.9 |
| Male/Female ratio | 0.9:1 | 1.0:1 | 1.0:1 |
| Married couples | 45% | 50% | 66% |
| Families w/ kids at home | 40% | 40% | 43% |
| Speak English only | 0.0% | 4.7% | 68.8% |
| Speak French only | 79.4% | 49.5% | 4.5% |
| Data | Percent |
| Black | 1.3% |
| N/A | 0.0% |
| Data | Percent |
| Germany | 1.3% |
| France | 0.6% |
| Haiti | 0.2% |
| Other Western Africa | 0.1% |
| Bosnia Herzegovina | 0.1% |