Population
Population
topographic
Population

San Mateo County

764,442
Total Population in 2020
In 2020, San Mateo County was home to 764,442 people. Residents were predominantly working age, while those under 18 were a larger segment of the county than those 65 and older. The population was diverse, with no racial group in the majority.

Most Populous Demographics

CategoryDemographicTotalPercentage
Age18-64483,92063%
SexFemale386,89651%
Race and Hispanic or LatinoWhite (Not Hispanic or Latino)275,90236%

Age

39.9
Median Age
In 2020, San Mateo County's population was a majority working-age adults, while those under age 18 were a moderately larger share of the county than those 65 and older. Looking at 10-year age ranges, 30-39 was the largest group.

Population by Age Range

030k60k90k120k0-910-1920-2930-3940-4950-5960-6970-7980+11%11%13%15%14%13%11%7%4%
030k60k90k120k11%11%13%15%14%13%11%7%4%0-910-1920-2930-3940-4950-5960-6970-7980+
/View Population by Age Range dynamic table

Population by Age Group

63%
18-64
    154,206
    Under 18
    483,920
    18-64
    126,316
    65 and over
/View Population by Age Group dynamic table

Table: Population by Age Range

Age RangePopulation in San Mateo County
TotalPercentage
0-982,57811%
10-1987,65811%
20-2995,60413%
30-39117,82915%
40-49105,39514%
50-59102,55313%
60-6985,86911%
70-7954,5477%
80+32,4094%

Table: Population by Age Group

Age GroupPopulation in San Mateo County
TotalPercentage
Under 18154,20620%
18-64483,92063%
65 and over126,31617%
* For both charts above, the data is collected from the U.S. Census Bureau Decennial Data 2020, Demographic and Housing Characteristics File (DHC), P12 Sex by Age for Selected Age Categories.

Sex and Age

In 2020, females outnumbered males by a moderate amount in San Mateo County. Males 30-39 were the largest group by age, followed by females 30-39 and females 40-49. The biggest gap was in the 80-and-older age group, where females were the larger share.

Population by Sex

51%
Female
    377,546
    Male
    386,896
    Female
/View Population by Sex dynamic table

Population by Sex and Age

020k40k60k80k0-910-1920-2930-3940-4950-5960-6970-7980+42,52445,09849,69260,34452,17749,74440,85124,36712,74940,05442,56045,91257,48553,21852,80945,01830,18019,660
020k40k60k80k0-910-1920-2930-3940-4950-5960-6970-7980+42,52445,09849,69260,34452,17749,74440,85124,36712,74940,05442,56045,91257,48553,21852,80945,01830,18019,660
80k60k40k20k020k40k60k80k0-910-1920-2930-3940-4950-5960-6970-7980+42,52445,09849,69260,34452,17749,74440,85124,36712,74940,05442,56045,91257,48553,21852,80945,01830,18019,660
/View Population by Sex and Age dynamic table
Male
Female

Table: Population by Sex

SexSan Mateo County
TotalPercentage
Male377,54649%
Female386,89651%

Table: Population by Sex and Age

Sex and AgeSan Mateo County
TotalPercentage
Male377,54649%
Male: 0-942,5246%
Male: 10-1945,0986%
Male: 20-2949,6927%
Male: 30-3960,3448%
Male: 40-4952,1777%
Male: 50-5949,7447%
Male: 60-6940,8515%
Male: 70-7924,3673%
Male: 80+12,7492%
Female386,89651%
Female: 0-940,0545%
Female: 10-1942,5606%
Female: 20-2945,9126%
Female: 30-3957,4858%
Female: 40-4953,2187%
Female: 50-5952,8097%
Female: 60-6945,0186%
Female: 70-7930,1804%
Female: 80+19,6603%
* For both charts above, the data is collected from the U.S. Census Bureau Decennial Data 2020, Demographic and Housing Characteristics File (DHC), P12 Sex by Age for Selected Age Categories.

Race and Hispanic or Latino

36%
White (Not Hispanic or Latino)
In 2020, San Mateo County had a diverse population with no race/ethnicity being a majority. White and Asian people were the largest groups in the county, while Hispanic and other/multiracial residents were the next biggest segments of the population.

Population by Race and Hispanic or Latino

070k140k210k280kWhite*Black or African American*American Indian / Alaska Native*Asian*Native Hawaiian / Pacific Islander*Other / Multi-racial*Hispanic or Latino (any race)36%2%<1%30%1%6%25%
070k140k210k280kWhite*Black or African American*American Indian / Alaska Native*Asian*Native Hawaiian / Pacific Islander*Other / Multi-racial*Hispanic or Latino (any race)36%2%<1%30%1%6%25%
070k140k210k280kWhite*Black or African American*American Indian / Alaska Native*Asian*Native Hawaiian / Pacific Islander*Other / Multi-racial*Hispanic or Latino (any race)36%2%<1%30%1%6%25%
/View Population by Race and Hispanic or Latino dynamic table

Table: Population by Race and Hispanic or Latino

Race and Hispanic or LatinoPopulation in San Mateo County
TotalPercentage
White275,90236%
Black or African American14,7012%
American Indian / Alaska Native1,021<1%
Asian227,78330%
Native Hawaiian / Pacific Islander8,8401%
Other / Multi-racial44,8096%
Hispanic or Latino (any race)191,38625%
* Categorized as Not Hispanic. This means that all the racial groups marked with an asterisk — White, Black or African American, American Indian / Alaska Native, Asian, Native Hawaiian / Pacific Islander, and Other / Multi-racial — do not include individuals who identify as Hispanic or Latino. The "Hispanic or Latino (any race)" category is separate, as Hispanic/Latino is considered an ethnicity rather than a racial category. For the chart above, the data is collected from the U.S. Census Bureau Decennial Data 2020, Demographic and Housing Characteristics File (DHC), P5 Hispanic or Latino Origin by Race.