Share of the population by age and sex, five-year groups

Population of Illinois, 2010–2025 · click to pick a year
Estimates up to 2019 are built on the 2010 Census, those from 2020 on the 2020 Census. A line that steps up or down between 2019 and 2020 reflects this re-basing, not a sudden change in population.

Year

-5 -1   2025  +1 +5

12,719,141 people lived in Illinois on July 1, 2025: the 6th-largest population among the 50 states and the District of Columbia. The median age was 39.7 years (United States: 39.4); more residents are 65 or older (18.7%) than under 15 (16.8%): an ageing, top-heavy pyramid. There were 96.3 men for every 100 women. Since 2010 the population has shrunk by 0.9%. Source: U.S. Census Bureau, Population Estimates Program, Vintage 2025 estimates (resident population on July 1; public domain). Median age, shares, dependency ratios and rankings are calculated by PopulationPyramid.net from these estimates; the Census Bureau does not endorse this site.

Key indicators, 2025
Population
12,719,141
Rank by population
6th of 51
Median age
39.7
Men per 100 women
96.3
Under 15
16.8%
15–64
64.5%
65 and over
18.7%
Child dependency
26.0
Old-age dependency
29.0
Change since 2010
-0.9%
Dependency ratios count children under 15 or adults 65 and over per 100 residents aged 15 to 64.
Show the population by age group, 2025
AgeMenWomenTotalShare
0-4330,401316,480646,8815.1%
5-9369,201356,796725,9975.7%
10-14387,506370,344757,8506.0%
15-19422,060398,050820,1106.4%
20-24437,883416,941854,8246.7%
25-29442,868434,086876,9546.9%
30-34438,425436,734875,1596.9%
35-39428,113429,093857,2066.7%
40-44414,825421,279836,1046.6%
45-49387,809398,158785,9676.2%
50-54371,704385,560757,2646.0%
55-59371,284388,035759,3196.0%
60-64379,321407,040786,3616.2%
65-69350,613391,511742,1245.8%
70-74282,318330,870613,1884.8%
75-79204,936256,219461,1553.6%
80-84120,040166,897286,9372.3%
85+99,960175,781275,7412.2%
How Illinois compares with similar-sized states, 2025
RankStateResidentsRelative
3 Florida 23,462,518
4 New York 20,002,427
5 Pennsylvania 13,059,432
6 Illinois 12,719,141
7 Ohio 11,900,510
8 Georgia 11,302,748
9 North Carolina 11,197,968
Frequently asked questions about Illinois's population
What is the population of Illinois?
Illinois had an estimated 12,719,141 residents on July 1, 2025, according to the U.S. Census Bureau, Population Estimates Program. That ranks 6th among the 51 states and the District of Columbia.
What is the median age in Illinois?
The median age in Illinois was 39.7 years in 2025, the 24th oldest of the 51 states and DC. That is 0.3 years older than the national median of 39.4.
How many people in Illinois are 65 or older?
About 2,379,145 residents of Illinois (18.7%) were 65 or older in 2025, against 16.8% under 15 and 64.5% aged 15 to 64.
What does the population pyramid of Illinois show?
In 2025, Illinois: more residents are 65 or older (18.7%) than under 15 (16.8%): an ageing, top-heavy pyramid. There were 96.3 men for every 100 women.
How fast is the population of Illinois changing?
The population of Illinois shrank by 0.9% between 2010 and 2025, and by 0.1% in the last year.
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