| | Spring Lake, NJ | Belmar, NJ | United States |
| Population | 2,814 | 5,869 | 329,725,481 |
| Female Population | 51.4% | 40.8% | 50.5% |
| Male Population | 48.6% | 59.2% | 49.5% |
| Median Age | 58.5 | 42.3 | 38.4 |
| space3 | | | |
| Population - 2010 | 2,993 | 5,806 | 309,327,143 |
| Population - 2000 | 3,567 | 6,045 | 285,036,114 |
| Population - 1990 | 3,499 | 5,877 | 251,960,433 |
| Pop. 2000 to Now | -19.0% | -8.4% | 15.6% |
| Pop. 1990 to Now | -17.4% | -5.7% | 30.8% |
| space4 | | | |
| Population Density | 2,112.6 | 5,616.3 | 93.4 |
| Land Area | 1.3 | 1.0 | 3,531,905.4 |
| Water Area | 0.4 | 0.6 | 264,836.8 |
| space | | | |
| Est. Total Population By Age | | | |
| | Spring Lake, NJ | Belmar, NJ | United States |
| Age 0 to 4 | 2.2% | 3.1% | 5.9% |
| Age 5 to 9 | 5.3% | 3.4% | 6.1% |
| Age 10 to 14 | 4.3% | 3.6% | 6.6% |
| Age 15 to 17 | 3.0% | 2.4% | 3.9% |
| Age 18 to 20 | 1.6% | 1.8% | 4.0% |
| Age 21 to 24 | 1.7% | 5.5% | 5.2% |
| Age 25 to 34 | 3.6% | 20.6% | 13.8% |
| Age 35 to 44 | 3.0% | 11.2% | 12.9% |
| Age 45 to 54 | 18.0% | 14.7% | 12.6% |
| Age 55 to 59 | 10.6% | 10.2% | 6.7% |
| Age 60 to 64 | 10.9% | 7.8% | 6.3% |
| Age 65 to 74 | 18.9% | 10.3% | 9.6% |
| Age 75 to 84 | 13.2% | 3.6% | 4.5% |
| Age 85 and over | 3.7% | 1.7% | 1.9% |
| space1 | | | |
| Race | | | |
| | Spring Lake, NJ | Belmar, NJ | United States |
| White | 93.1% | 81.0% | 59.4% |
| Black | 0.1% | 4.5% | 12.2% |
| Asian | 3.3% | 0.5% | 5.6% |
| Native American | 0.0% | 0.0% | 0.6% |
| Hawaiian, Pacific Islander | 0.0% | 0.0% | 0.2% |
| Other | 0.0% | 0.2% | 0.4% |
| Two or More Races | 2.9% | 0.3% | 3.2% |
| Hispanic | 0.6% | 13.4% | 18.4% |
| space2 | | | |
| Marriage & Family | | | |
| | Spring Lake, NJ | Belmar, NJ | United States |
| Married Population | 69.6% | 35.6% | 49.8% |
| Currently Married | 68.5% | 32.7% | 48.0% |
| Married but Separated | 1.0% | 2.9% | 1.8% |
| Single Population | 30.4% | 64.4% | 50.2% |
| Never Married | 15.7% | 48.4% | 33.8% |
| Divorced | 8.3% | 12.7% | 10.8% |
| Widowed | 6.4% | 3.3% | 5.6% |
| space5 | | | |
| Household Size | 2.18 | 2.20 | 2.60 |
| Households | 1,285 | 2,662 | 124,010,992 |
| Family Households | 899 | 1,189 | 80,755,759 |
| Married couple, w/children | 19.5% | 15.3% | 30.5% |
| Married couple, no children | 71.7% | 48.3% | 42.9% |
| Non Family Households | 386 | 1,473 | 43,255,233 |
| Single householder, w/children | 3.4% | 13.0% | 15.8% |
| Single householder, no children | 5.3% | 23.5% | 10.8% |