San Mateo County, California

San Mateo County, California, had an estimated population of 743,568 in 2025 across 1,162 km². The figures below come from the US Census Bureau's population estimates and the American Community Survey, each shown with its own vintage and its rank among California's counties and nationally.

Population: 743,568; 2025 estimate
Area: 1,162 km²
Density: 640; per km²
Median income: $158,855; household, ACS 2024
Median age: 40.9; years, ACS 2024

How California's counties spread

Amenities & Infrastructure

Indicator	Value	In California	In the US
Households with Broadband2024	95.7%	2 / 58	30 / 3,144
Median Gross Rent2024	$2,922	1 / 56	1 / 3,137
Median Home Value2024	$1,559,600	1 / 58	3 / 3,139
Owner-Occupied Homes2024	58.5%	42 / 58	2,969 / 3,144
Vacant Homes2024	7.9%	37 / 58	2,543 / 3,144

Demography

Indicator	Value	In California	In the US
Aged 65 and Over2024	17.8%	27 / 58	2,221 / 3,144
American Indian & Alaska Native2024	0.1%	51 / 58	1,566 / 3,144
Asian, non-Hispanic2024	31.0%	4 / 58	6 / 3,144
Average Household Size2024people	2.8	27 / 58	273 / 3,144
Black, non-Hispanic2024	2.0%	23 / 58	1,582 / 3,144
Foreign-Born2024	35.7%	2 / 58	9 / 3,144
Hispanic or Latino2024	24.9%	34 / 58	332 / 3,144
Median Age2024years	40.9	21 / 58	1,742 / 3,144
Sex Ratio2024per 1,000 males	1,007	22 / 58	1,368 / 3,144
Speak a Language Other Than English2024	45.8%	10 / 58	77 / 3,144
Under 182024	19.5%	39 / 58	2,407 / 3,144
Veterans2024	2.9%	55 / 58	3,096 / 3,144
White, non-Hispanic2024	34.7%	41 / 58	2,963 / 3,144

Economy

Indicator	Value	In California	In the US
Below Poverty Line2024	6.7%	56 / 58	2,964 / 3,144
Households on SNAP2024	5.1%	57 / 58	2,838 / 3,144
Income Inequality2024index	0.497	6 / 58	273 / 3,144
Median Household Income2024	$158,855	2 / 58	3 / 3,143
Per Capita Income2024	$84,288	3 / 58	8 / 3,144
Unemployment Rate2024	4.8%	52 / 58	1,259 / 3,144

Education

Indicator	Value	In California	In the US
Bachelor's Degree or Higher2024	53.7%	4 / 58	63 / 3,144
High School or Higher2024	90.2%	19 / 58	1,575 / 3,144

Health Coverage

Indicator	Value	In California	In the US
No Health Insurance2024	3.8%	54 / 58	2,924 / 3,144
With a Disability2024	9.4%	55 / 58	3,050 / 3,144

Population & Density

Indicator	Value	In California	In the US
Population2025	743,568	15 / 58	93 / 3,144
Population Density2025/km²	640	6 / 58	94 / 3,144

Work & Commute

Indicator	Value	In California	In the US
Commute by Public Transit2024	5.1%	4 / 58	54 / 3,144
Households with No Vehicle2024	5.8%	23 / 58	1,326 / 3,144
Mean Commute Time2024minutes	26.4	27 / 58	1,054 / 3,143
Work from Home2024	24.3%	5 / 58	55 / 3,144

Other counties of California

Compare San Mateo County against every other county on a map, add layers and run a scatter — open the atlas. Sources and vintages for every figure on this page are listed under datasets, or browse all 3,144 counties.