| Statistic | Leslie Valley | Newmarket | Ontario |
| Population | 11,303 | 88,702 | 14,804,681 |
| Population density (sq km) | 2,766 | 2,331 | 15 |
| Median age | 46.9 | 40.6 | 40.9 |
| Male/Female ratio | 1.1:1 | 1.1:1 | 1.0:1 |
| Married couples | 71% | 73% | 71% |
| Families w/ kids at home | 48% | 53% | 46% |
| Speak English only | 90.4% | 90.2% | 86.1% |
| Speak French only | 0.0% | 0.0% | 0.3% |
| Data | Percent |
| Chinese | 5.5% |
| South Asian | 3.7% |
| Black | 3.3% |
| Southeast Asian | 3.1% |
| West Asian | 1.6% |
| Data | Percent |
| United Kingdom | 3.3% |
| China | 1.7% |
| Iran | 1.5% |
| Philippines | 1.2% |
| India | 1.0% |