Demographics · CA
San Mateo, CA demographics: 103,105 residents, with a median age of 38.3 years, from the U.S. Census Bureau's American Community Survey 2020–2024 (5-year estimates).
103,105people live in San Mateo, at a median age of 38.3 years (American Community Survey 2020–2024, a 5-year average)
Median age 38.3 years — younger than the U.S. median of 38.9.
ACS 2020–2024 5-year · ACS 5-Year Estimates 2020-2024 (released 2026-01-29)
In San Mateo, the largest race group is White (37.9%); 27.6% of residents are Hispanic or Latino (of any race); 36.2% were born outside the United States.
ACS 2020–2024 · B01001 / B01002
The median age in San Mateo is 38.3 years (±0.7), younger than the U.S. median of 38.9 years. The population is 49.5% male and 50.5% female. The largest age band is 25 to 34 at 17.4%.
| Age band | People | Share | ± margin |
|---|---|---|---|
| Under 5 | 6,099 | 5.9% | ±561 |
| 5 to 17 | 14,112 | 13.7% | ±913 |
| 18 to 24 | 7,338 | 7.1% | ±718 |
| 25 to 34 | 17,911 | 17.4% | ±1,014 |
| 35 to 44 | 15,794 | 15.3% | ±966 |
| 45 to 54 | 12,937 | 12.5% | ±790 |
| 55 to 64 | 11,351 | 11.0% | ±747 |
| 65 to 74 | 8,909 | 8.6% | ±615 |
| 75 and over | 8,654 | 8.4% | ±644 |
Median age by sex: 36.4 (male) · 40.2 (female).
Shares may not sum to 100% due to rounding. Source: U.S. Census Bureau, ACS 5-Year 2020–2024 (B01001 sex by age, B01002 median age) · place-grain · margins of error at the 90% confidence level · methodology →
ACS 2020–2024 · B02001 / B03003
The largest race group in San Mateo is White at 37.9% of the population. Separately, 27.6% of residents are Hispanic or Latino of any race.Race and Hispanic origin are two different questions on the census form, so their shares are reported separately and are not additive.
| Race (alone, or two or more) | People | Share | ± margin |
|---|---|---|---|
| White alone | 39,112 | 37.9% | ±1,780 |
| Black or African American alone | 1,489 | 1.4% | ±337 |
| American Indian & Alaska Native alone | 1,703 | 1.7% | ±597 |
| Asian alone | 29,226 | 28.3% | ±1,567 |
| Native Hawaiian & Pacific Islander alone | 1,432 | 1.4% | ±445 |
| Some other race alone | 13,778 | 13.4% | ±1,848 |
| Two or more races | 16,365 | 15.9% | ±1,273 |
| Hispanic or Latino (of any race) | 28,418 | 27.6% | ±1,941 |
Race shares may not sum to 100% due to rounding; race and Hispanic origin are separate questions and are not additive. Source: U.S. Census Bureau, ACS 5-Year 2020–2024 (B02001 race, B03003 Hispanic or Latino origin) · place-grain · margins of error at the 90% confidence level · methodology →
ACS 2020–2024 · B11001 / B25010
San Mateo has 39,895 households. 62.2% are family households and 29.5% are people living alone. The average household holds 2.54 people.
Total households
39,895
ACS 2020–2024 5-yr · B11001
Avg household size
2.54
ACS 2020–2024 5-yr · B25010 · ±0.05
Family households
62.2%
Share of all households · B11001
Living alone
29.5%
Share of all households · B11001
| Household type | Households | ± margin |
|---|---|---|
| Total households | 39,895 | ±820 |
| Family households | 24,811 | ±643 |
| Nonfamily households | 15,084 | ±1,012 |
| Householder living alone | 11,763 | ±941 |
Source: U.S. Census Bureau, ACS 5-Year 2020–2024 (B11001 household type, B25010 average household size) · place-grain · methodology →
ACS 2020–2024 · B05002 / C16001
36.2% of San Mateo residents were born outside the United States. 53.4% of residents age 5 and over speak only English at home. The most-spoken non-English language at home is Spanish (20.5%).
| Measure | Value | Source / grain |
|---|---|---|
| Foreign-born share | 36.2% | 37,355 people · B05002 |
| Speak only English at home (age 5+) | 53.4% | C16001 |
| Top non-English language at home | 20.5% | Spanish · 19,909 speakers · C16001 |
Source: U.S. Census Bureau, ACS 5-Year 2020–2024 (B05002 place of birth, C16001 language spoken at home) · place-grain · methodology →
ACS 2020–2024 · B15003
57.8% of adults age 25 and over in San Mateo hold a bachelor's degree or higher (the U.S. share is about 35%).
| Measure | Value | Source / grain |
|---|---|---|
| Bachelor's degree or higher (age 25+) | 57.8% | B15003 lines 22–25 over line 1 · place-grain |
Source: U.S. Census Bureau, ACS 5-Year 2020–2024 (B15003 educational attainment, population 25+) · place-grain · methodology →
Sources · provenance
The GEOID for San Mateo is 0668252. Every figure on this page is a place-grain American Community Survey 5-Year 2020–2024 estimate (ACS 5-Year Estimates 2020-2024 (released 2026-01-29)) shown with its margin of error. Full per-dataset detail: /sources/.