• county
  • FIPS 06081
  • Largest town: San Mateo

San Mateo County, California

San Mateo County had 742,893 residents in the Census Vintage 2024 estimate, on 448.6 square miles of land. It ranks 15th of 58 in California by population and 56th by land area.

Population
742,893
#15 of 58 in California · #91 in US
Area
448.6 sq mi
#56 of 58 in California · #2,277 in US
Density
1,656 / sq mi
#6 of 58 in California · #94 in US
Median household income
$151,004
#2 of 58 in California · #3 in US

Census Vintage 2024 estimates · SAIPE 2023 income · 2024 Gazetteer land area

San Mateo County within California. Pin: Sacramento.

Measure from here

Tools and pages that start from San Mateo County

San Mateo County population, land area and income

San Mateo County had 742,893 residents in the Census Vintage 2024 estimate, on 448.6 square miles of land. It ranks 15th of 58 in California by population and 56th by land area. That works out to 1,656.0 people per square mile, 17.2 times the US average of 96.3, and in the top tenth nationally.

The median county-equivalent in California has 187,274 residents, so San Mateo County is 4.0 times that size.

Its SAIPE 2023 median household income of $151,004 is the 3rd highest among 3,143 counties with an estimate.

National rank among 3,144

Population

742,893

3144th1st

91st of 3,144 (US)

Land area

449 sq mi

3144th1st

2277th of 3,144 (US)

Density

1,656.0 / sq mi

3144th1st

94th of 3,144 (US)

Median household income

$151,004

3143rd1st

3rd of 3,143 (US)

Rank within California (58)

Population

742,893

58th1st

15th of 58 (CA)

Land area

449 sq mi

58th1st

56th of 58 (CA)

Density

1,656.0 / sq mi

58th1st

6th of 58 (CA)

Median household income

$151,004

58th1st

2nd of 58 (CA)

How San Mateo County's population changed since 2020

San Mateo County lost 19,834 residents between the July 2020 and July 2024 estimates, a drop of 2.6%. That ranks 46th of 58 in California for growth. The median California county changed by -0.6%, and the state as a whole by -0.2%.

Since the April 2020 estimates base, San Mateo County recorded 31,448 births and 21,735 deaths, a natural change of +9,713. Net international migration added +32,427 and net domestic migration, people moving to or from other US counties, came to -62,967. The largest single component was domestic migration, which removed 62,967 people.

762.7k2020739.3k2021732.5k2022734.3k2023742.9k2024
Census Vintage 2024 county estimates for July 1 of each year. The axis starts above zero so year-to-year changes are visible.

Components of change, April 2020 to July 2024

Births
31,448
Deaths
21,735
Net international migration
+32,427
Net domestic migration
-62,967
Change, July 2023 to July 2024
+8,626

Where San Mateo County is

The Census internal point of San Mateo County is at 37.414700, -122.371500. It sits in UTM zone 10N. The map shades California's 58 county-equivalents by population change from 2020 to 2024, darker for faster growth, with San Mateo County outlined. Dots are towns of 1,000+ people with residents in it.

Los Angeles County: -2.4%Kings County: +1.4%Sierra County: -3.6%Riverside County: +4.3%Santa Barbara County: -0.8%San Bernardino County: +1.4%Nevada County: -0.1%Santa Clara County: +0.1%Yuba County: +6.7%Fresno County: +1.4%Plumas County: -4.7%Monterey County: -1.0%Amador County: +3.6%Alameda County: -1.9%Tulare County: +2.0%San Joaquin County: +4.5%Alpine County: -6.8%Siskiyou County: -3.4%Butte County: -0.9%Kern County: +1.8%San Diego County: -0.1%Sacramento County: +1.5%Ventura County: -1.0%Yolo County: +3.4%Lake County: -0.6%Napa County: -3.4%Tehama County: -1.9%San Francisco County: -5.4%El Dorado County: +0.8%Calaveras County: +2.5%Inyo County: -2.7%Shasta County: -0.6%Lassen County: -12.3%San Luis Obispo County: -0.0%Mariposa County: -0.5%Trinity County: -2.8%Contra Costa County: +0.6%Mendocino County: -2.4%Imperial County: +1.1%Santa Cruz County: -3.4%Placer County: +6.9%Orange County: -0.5%San Benito County: +7.2%Marin County: -1.9%San Mateo County: -2.6%Colusa County: +0.9%Del Norte County: -2.2%Solano County: +0.5%Glenn County: -2.0%Tuolumne County: -2.7%Sonoma County: -0.6%Humboldt County: -2.9%Mono County: -1.8%Stanislaus County: +0.6%Merced County: +4.9%Sutter County: -0.9%Madera County: +5.8%Modoc County: -2.1%
Change 2020 to 2024
  1. < -2.7%
  2. < -1.0%
  3. < -0.0%
  4. < +1.5%
  5. ≥ +1.5%
no data

Orange pin: San Mateo County internal point. Dark pin: Sacramento.

Internal point

Decimal
37.414700, -122.371500
DMS
37°24'52.92"N 122°22'17.40"W
UTM
10N 555616.6E 4141063.3N
Geohash
9q8uz75u3
Plus code
849VCJ7H+VC

Towns in San Mateo County

20 incorporated places of 1,000+ people have residents in San Mateo County, 681,908 people together, or 92% of the county. Each figure counts only the part of the town inside San Mateo County; towns marked "part" extend into another county. The largest is San Mateo with 103,006.

  1. 01San Mateo103,006
  2. 02Daly City101,418
  3. 03Redwood City82,982
  4. 04South San Francisco64,660
  5. 05San Bruno42,035
  6. 06Pacifica37,056
  7. 07Menlo Park33,040
  8. 08Foster City32,657
  9. 09Burlingame30,885
  10. 10San Carlos29,403
  11. 11East Palo Alto29,296
  12. 12Belmont27,132
  13. 13Millbrae23,321
  14. 14Half Moon Bay11,324
  15. 15Hillsborough11,171
Census Vintage 2024 subcounty estimates, county parts of incorporated places (SUMLEV 157).

Counties bordering San Mateo County

The Census 2024 county adjacency file lists 4 neighbors for San Mateo County. The most populous is Santa Clara County, CA, with 1,926,325 residents. Distances run between Census internal points in a straight line.

Distance to Sacramento and the nearest big city

Sacramento is 93.4 miles NNE of San Mateo County's internal point in a straight line. The nearest place of 100,000 or more is San Mateo, CA (population 103,006), 10.6 miles away. The nearest place of 10,000 or more is Half Moon Bay, CA (population 11,324), 5.2 miles away.

San Mateo County FIPS code

The FIPS code of San Mateo County is 06081: state code 06 for California plus county code 081. Use it as text, with the leading zero, when joining Census, BLS, or CDC county tables. SAIPE lists its 2023 median household income as $151,004.

Questions people ask

What is the population of San Mateo County, California?

The Census Vintage 2024 estimate for July 1, 2024 is 742,893. That is down 19,834 people (2.6%) from the July 2020 estimate of 762,727.

What is the FIPS code of San Mateo County?

06081. The first two digits (06) are California; the last three (081) identify the county.

What is the largest town in San Mateo County?

San Mateo, with 103,006 residents inside San Mateo County in 2024.

Which counties border San Mateo County?

4 county-equivalents border it in the Census 2024 adjacency file: Santa Clara County, CA; Alameda County, CA; San Francisco County, CA; Santa Cruz County, CA.

Sources and data as of

Data as of: Census Vintage 2024 population estimates, 2024 Gazetteer land area and internal points, SAIPE 2023 median household income.

  1. 01Census Vintage 2024 county population estimates
  2. 02Census 2024 Gazetteer, counties
  3. 03Census SAIPE 2023 state and county estimates
  4. 04Census Vintage 2024 subcounty population estimates
  5. 05Census 2024 county adjacency file
  6. 06Census 2024 cartographic boundary file, counties (1:5,000,000)

How every number is computed: methodology. Spotted a wrong figure? Report an error.