US Population By Age Group and Age Cohort in 2021 (ACS-5Yrs)

Updated on June 29, 2024.

Based on the US Census ACS-5Yrs estimates, in 2021, among the 329.73M US population, the 25-29yrs age group constituted the highest percentage of the total population (6.93%), followed by the 30-34yrs age group (6.83%), and the 55-59yrs age group (6.65%).

In the case of age cohorts, Adults (18-64yrs) constituted the highest percentage of the total population (61.45%), followed by Children (0-17yrs) (22.51%), and Seniors (65yrs and Over) (16.04%).

The first and second charts below shows the percentage of the population by age group and age cohort respectively. The table below also shows the number and percentages for each age group and age cohort.

You can see similar information for each state.

US Percentages of Population By Age Group in 2021
25-29yrs
30-34yrs
55-59yrs
35-39yrs
10-14yrs
15-19yrs
20-24yrs
50-54yrs
60-64yrs
45-49yrs
US Percentages of Population By Age Cohort in 2021
Adults (18-64yrs)
Children (0-17yrs)
Seniors (65yrs and Over)
US Population By Age Group in 2021
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Age Group Number of People % of Total
25-29yrs 22854328 6.93
30-34yrs 22506614 6.83
55-59yrs 21928936 6.65
35-39yrs 21920290 6.65
10-14yrs 21674117 6.57
15-19yrs 21654363 6.57
20-24yrs 21574425 6.54
50-54yrs 21049271 6.38
60-64yrs 20900477 6.34
45-49yrs 20582187 6.24
40-44yrs 20521593 6.22
5-9yrs 20247138 6.14
Under 5yrs 19423121 5.89
65-69yrs 17634322 5.35
70-74yrs 13956297 4.23
75-79yrs 9066018 2.75
85yrs and Over 6299788 1.91
80-84yrs 5932196 1.80
US Population By Age Cohort in 2021
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Age Cohort Number of People % of Total
Adults (18-64yrs) 202602785 61.45
Children (0-17yrs) 74234075 22.51
Seniors (65yrs and Over) 52888621 16.04