• county
  • FIPS 08013
  • Largest town: Boulder

Boulder County, Colorado

Boulder County had 330,262 residents in the Census Vintage 2024 estimate, on 726.4 square miles of land. It ranks 9th of 64 in Colorado by population and 52nd by land area.

Population
330,262
#9 of 64 in Colorado · #226 in US
Area
726.4 sq mi
#52 of 64 in Colorado · #1,222 in US
Density
455 / sq mi
#7 of 64 in Colorado · #307 in US
Median household income
$97,170
#12 of 64 in Colorado · #162 in US

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

Boulder County within Colorado. Pin: Denver.

Measure from here

Tools and pages that start from Boulder County

Boulder County population, land area and income

Boulder County had 330,262 residents in the Census Vintage 2024 estimate, on 726.4 square miles of land. It ranks 9th of 64 in Colorado by population and 52nd by land area. That works out to 454.6 people per square mile, 4.7 times the US average of 96.3, and in the top tenth nationally.

The median county-equivalent in Colorado has 15,336 residents, so Boulder County is 21.5 times that size.

Its SAIPE 2023 median household income of $97,170 is in the top tenth among 3,143 counties with an estimate.

National rank among 3,144

Population

330,262

3144th1st

226th of 3,144 (US)

Land area

726 sq mi

3144th1st

1222nd of 3,144 (US)

Density

454.6 / sq mi

3144th1st

307th of 3,144 (US)

Median household income

$97,170

3143rd1st

162nd of 3,143 (US)

Rank within Colorado (64)

Population

330,262

64th1st

9th of 64 (CO)

Land area

726 sq mi

64th1st

52nd of 64 (CO)

Density

454.6 / sq mi

64th1st

7th of 64 (CO)

Median household income

$97,170

64th1st

12th of 64 (CO)

How Boulder County's population changed since 2020

Boulder County lost 691 residents between the July 2020 and July 2024 estimates, a drop of 0.2%. That ranks 42nd of 64 in Colorado for growth. The median Colorado county changed by +1.7%, and the state as a whole by +2.9%.

Since the April 2020 estimates base, Boulder County recorded 10,393 births and 9,132 deaths, a natural change of +1,261. Net international migration added +6,437 and net domestic migration, people moving to or from other US counties, came to -7,972. The largest single component was domestic migration, which removed 7,972 people.

331.0k2020327.1k2021328.0k2022328.4k2023330.3k2024
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
10,393
Deaths
9,132
Net international migration
+6,437
Net domestic migration
-7,972
Change, July 2023 to July 2024
+1,843

Where Boulder County is

The Census internal point of Boulder County is at 40.095000, -105.397700. It sits in UTM zone 13N. The map shades Colorado's 64 county-equivalents by population change from 2020 to 2024, darker for faster growth, with Boulder County outlined. Dots are towns of 1,000+ people with residents in it.

Otero County: -3.6%Lake County: -0.6%Adams County: +4.3%Kit Carson County: +0.2%Phillips County: -0.9%Bent County: +5.5%Lincoln County: -1.1%Washington County: -0.9%Hinsdale County: -5.1%Alamosa County: +1.9%Kiowa County: -4.1%Arapahoe County: +1.8%Archuleta County: +5.1%Montrose County: +4.6%Jefferson County: -0.8%Gilpin County: +2.5%Larimer County: +4.1%Custer County: +17.5%Saguache County: +4.3%Mineral County: +7.1%Broomfield County: +5.1%Logan County: -2.1%Mesa County: +3.4%Eagle County: -2.4%Denver County: +1.6%Pitkin County: -4.2%Boulder County: -0.2%El Paso County: +2.6%Las Animas County: +0.1%San Miguel County: -2.9%Douglas County: +9.3%Cheyenne County: -1.9%Garfield County: +2.2%Ouray County: +6.5%San Juan County: +16.0%Yuma County: +0.8%Elbert County: +12.1%Prowers County: -0.5%Morgan County: +4.2%Delta County: +3.7%Chaffee County: +6.6%Huerfano County: +2.4%Teller County: +0.5%Costilla County: +5.3%Baca County: -3.3%Routt County: +1.6%Conejos County: +1.3%Summit County: -1.1%Clear Creek County: -3.0%Fremont County: +2.5%Rio Blanco County: +1.3%Dolores County: +5.8%Grand County: +2.6%Gunnison County: +2.1%Park County: +5.1%Sedgwick County: -5.5%Montezuma County: +3.7%La Plata County: +2.1%Moffat County: -1.0%Rio Grande County: -3.6%Weld County: +11.5%Pueblo County: +0.9%Jackson County: -7.6%Crowley County: -1.5%
Change 2020 to 2024
  1. < -1.9%
  2. < +0.5%
  3. < +2.4%
  4. < +5.1%
  5. ≥ +5.1%
no data

Orange pin: Boulder County internal point. Dark pin: Denver.

Internal point

Decimal
40.095000, -105.397700
DMS
40°05'42.00"N 105°23'51.72"W
UTM
13N 466099.5E 4438377.2N
Geohash
9xjh1e5dr
Plus code
85GP3JW2+2W

Towns in Boulder County

8 incorporated places of 1,000+ people have residents in Boulder County, 288,889 people together, or 87% of the county. Each figure counts only the part of the town inside Boulder County; towns marked "part" extend into another county. The largest is Boulder with 106,803.

  1. 01Boulder106,803
  2. 02Longmont (part)98,503
  3. 03Lafayette30,587
  4. 04Louisville20,811
  5. 05Erie (part)14,889
  6. 06Superior13,654
  7. 07Lyons2,155
  8. 08Nederland1,487
Census Vintage 2024 subcounty estimates, county parts of incorporated places (SUMLEV 157).

Counties bordering Boulder County

The Census 2024 county adjacency file lists 6 neighbors for Boulder County. The most populous is Jefferson County, CO, with 578,533 residents. Distances run between Census internal points in a straight line.

Distance to Denver and the nearest big city

Denver is 32.9 miles SE of Boulder County's internal point in a straight line. The nearest place of 100,000 or more is Boulder, CO (population 106,803), 9.1 miles away.

Boulder County FIPS code

The FIPS code of Boulder County is 08013: state code 08 for Colorado plus county code 013. Use it as text, with the leading zero, when joining Census, BLS, or CDC county tables. SAIPE lists its 2023 median household income as $97,170.

Questions people ask

What is the population of Boulder County, Colorado?

The Census Vintage 2024 estimate for July 1, 2024 is 330,262. That is down 691 people (0.2%) from the July 2020 estimate of 330,953.

What is the FIPS code of Boulder County?

08013. The first two digits (08) are Colorado; the last three (013) identify the county.

What is the largest town in Boulder County?

Boulder, with 106,803 residents inside Boulder County in 2024.

Which counties border Boulder County?

6 county-equivalents border it in the Census 2024 adjacency file: Jefferson County, CO; Larimer County, CO; Weld County, CO; Broomfield County, CO; Grand County, CO; Gilpin County, CO.

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.