Counties in Idaho by average household size

Madison County had the highest average household size of 44 counties in 2021, at 4.5 persons per household. Clearwater County had the lowest, at 2.3 persons per household. The median was 2.7 persons per household and the figure for Idaho was 2.7 persons per household. Source: the U.S. Census Bureau.

Highest4.5Madison County

Lowest2.3Clearwater County

Median2.744 counties

Idaho2.7History

Map of counties, 2021

Under 2.4
2.4 to 2.6
2.6 to 2.7
2.7 to 2.9
2.9 to 3
3 and over

persons per household, 2021. Source: U.S. Census Bureau, American Community Survey 5-year estimates, table B25010: average household size of occupied housing units. Boundaries: U.S. Census Bureau cartographic boundary files.

All counties, 2021

persons per household. Source: U.S. Census Bureau, American Community Survey 5-year estimates, table B25010: average household size of occupied housing units. Retrieved 2026-10-12.

Full ranking

Rank	Counties	2021 persons per household
1	Madison County	4.5
2	Jefferson County	3.3
3	Camas County	3.1
4	Franklin County	3.1
5	Valley County	3.1
6	Bingham County	3
6	Jerome County	3
8	Cassia County	3
9	Fremont County	3
10	Canyon County	2.9
11	Clark County	2.9
11	Minidoka County	2.9
11	Power County	2.9
14	Bonneville County	2.9
15	Lincoln County	2.9
16	Gooding County	2.8
17	Bear Lake County	2.8
18	Caribou County	2.8
19	Owyhee County	2.8
20	Teton County	2.7
21	Twin Falls County	2.7
22	Butte County	2.7
23	Blaine County	2.7
24	Gem County	2.7
24	Payette County	2.7
26	Benewah County	2.7
27	Bannock County	2.6
27	Boundary County	2.6
29	Elmore County	2.6
30	Ada County	2.6
30	Kootenai County	2.6
32	Oneida County	2.6
33	Adams County	2.5
34	Washington County	2.5
35	Idaho County	2.5
36	Bonner County	2.5
37	Custer County	2.4
38	Nez Perce County	2.4
39	Shoshone County	2.4
40	Latah County	2.3
41	Lemhi County	2.3
42	Lewis County	2.3
43	Boise County	2.3
44	Clearwater County	2.3

Other periods

2024
2023
2022
2021

About this ranking

Average number of persons per private household. EU countries: EU-SILC. United States: American Community Survey five-year estimate of people in households divided by occupied housing units, where the period shown is the last year of the five-year span.

Covers private households only; people living in institutions or other group quarters are excluded. EU-SILC figures refer to the survey year. The EU and US surveys differ, so their figures are not strictly comparable.

Every value in the ranking comes from the same publisher and the same period, so the counties are compared on one definition. Equal values share a rank.

How to cite

U.S. Census Bureau. American Community Survey 5-year estimates, table B25010: average household size of occupied housing units. https://www2.census.gov/programs-surveys/acs/summary_file/2021/table-based-SF/data/5YRData/acsdt5y2021-b25010.dat. Retrieved 2026-10-12.

Citation styles

The publisher is the author. Invokely is named only as the place the figures were read, where a style asks for it.

APA 7

U.S. Census Bureau. (2026). American Community Survey 5-year estimates, table B25010: average household size of occupied housing units (Counties in Idaho by average household size, 2021) [Data set]. Retrieved October 12, 2026, from https://www2.census.gov/programs-surveys/acs/summary_file/2021/table-based-SF/data/5YRData/acsdt5y2021-b25010.dat

MLA 9

American Community Survey 5-year estimates, table B25010: average household size of occupied housing units, Counties in Idaho by average household size, 2021. U.S. Census Bureau, 29 Jan. 2026, https://www2.census.gov/programs-surveys/acs/summary_file/2021/table-based-SF/data/5YRData/acsdt5y2021-b25010.dat. Invokely, https://invokely.ai/rankings/average-household-size/idaho-counties?period=2021. Accessed 12 Oct. 2026.

Chicago (author-date)

U.S. Census Bureau. 2026. American Community Survey 5-year estimates, table B25010: average household size of occupied housing units. Counties in Idaho by average household size, 2021. Dataset. Accessed October 12, 2026. https://www2.census.gov/programs-surveys/acs/summary_file/2021/table-based-SF/data/5YRData/acsdt5y2021-b25010.dat. Also distributed by Invokely, https://invokely.ai/rankings/average-household-size/idaho-counties?period=2021.

Harvard

U.S. Census Bureau (2026) American Community Survey 5-year estimates, table B25010: average household size of occupied housing units, Counties in Idaho by average household size, 2021 [Dataset]. Available at: https://www2.census.gov/programs-surveys/acs/summary_file/2021/table-based-SF/data/5YRData/acsdt5y2021-b25010.dat, via Invokely: https://invokely.ai/rankings/average-household-size/idaho-counties?period=2021 (Accessed: 12 October 2026).

BibTeX

@misc{census_counties_in_idaho_by_2021,
  author = {{U.S. Census Bureau}},
  title = {{American Community Survey 5-year estimates, table B25010: average household size of occupied housing units: Counties in Idaho by average household size, 2021}},
  year = {2026},
  howpublished = {Data set},
  url = {https://www2.census.gov/programs-surveys/acs/summary_file/2021/table-based-SF/data/5YRData/acsdt5y2021-b25010.dat},
  urldate = {2026-10-12},
  note = {Accessed via Invokely, https://invokely.ai/rankings/average-household-size/idaho-counties?period=2021. Publisher attribution: U.S. Census Bureau. American Community Survey 5-year estimates, table B25010: average household size of occupied housing units. https://www2.census.gov/programs-surveys/acs/summary\_file/2021/table-based-SF/data/5YRData/acsdt5y2021-b25010.dat. Retrieved 2026-10-12.},
}

RIS

TY  - DATA
AU  - U.S. Census Bureau
TI  - American Community Survey 5-year estimates, table B25010: average household size of occupied housing units: Counties in Idaho by average household size, 2021
PY  - 2026
DA  - 2026/01/29
PB  - U.S. Census Bureau
DB  - Invokely
UR  - https://www2.census.gov/programs-surveys/acs/summary_file/2021/table-based-SF/data/5YRData/acsdt5y2021-b25010.dat
L2  - https://invokely.ai/rankings/average-household-size/idaho-counties?period=2021
Y2  - 2026/10/12
N1  - Accessed via Invokely, https://invokely.ai/rankings/average-household-size/idaho-counties?period=2021.
N1  - Publisher attribution: U.S. Census Bureau. American Community Survey 5-year estimates, table B25010: average household size of occupied housing units. https://www2.census.gov/programs-surveys/acs/summary_file/2021/table-based-SF/data/5YRData/acsdt5y2021-b25010.dat. Retrieved 2026-10-12.
ER  -

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Questions

Which county has the highest average household size?

Madison County, with 4.5 persons per household in 2021, according to the U.S. Census Bureau.

Which county has the lowest average household size?

Clearwater County, with 2.3 persons per household in 2021.

Where does this ranking come from?

Every value comes from one source and one period, so the places are comparable: U.S. Census Bureau, American Community Survey 5-year estimates, table B25010: average household size of occupied housing units. Retrieved 2026-10-12.