Fort Collins, CO population age distribution
A complete breakdown of Fort Collins's age demographics from 0 to 85 years, distributed across 18 age groups is listed in the table below.
Age Group | Population | % of Total Population |
---|---|---|
Under 5 years | 6,887 | 4.13% |
5 to 9 years | 8,398 | 5.04% |
10 to 14 years | 8,769 | 5.26% |
15 to 19 years | 14,719 | 8.82% |
20 to 24 years | 27,227 | 16.32% |
25 to 29 years | 17,515 | 10.5% |
30 to 34 years | 12,793 | 7.67% |
35 to 39 years | 10,276 | 6.16% |
40 to 44 years | 9,550 | 5.73% |
45 to 49 years | 8,078 | 4.84% |
50 to 54 years | 7,650 | 4.59% |
55 to 59 years | 8,430 | 5.05% |
60 to 64 years | 8,019 | 4.81% |
65 to 69 years | 6,677 | 4% |
70 to 74 years | 4,477 | 2.68% |
75 to 79 years | 3,017 | 1.81% |
80 to 84 years | 1,953 | 1.17% |
85 years and over | 2,353 | 1.41% |
TABLE OF CONTENTS
Fort Collins, CO population by age group
Sources: U.S. Census Bureau, American Community Survey (ACS) 2021

The largest age group in Fort Collins, CO was for the group of age 20-24 years with a population of 27,227 (16.32%), according to the 2021 American Community Survey.
At the same time, the smallest age group in Fort Collins, CO was the 80-84 years with a population of 1,953 (1.17%).
Fort Collins, CO population by age cohort
To better understand the age distribution of Fort Collins, CO's population, we divided it into the following 3 cohorts:
- Children : Under the age of 18 years
- Adults (working population): Between the age of 18 and 64 years
- Seniors: 65 years and above

Here's the population for each of the three cohorts.
Age Group | Population | % of Total Population |
---|---|---|
Under 18 years | 29,239 | 17.53% |
18 to 64 years | 119,072 | 71.39% |
85 years and over | 18,477 | 11.08% |
Key stats for each age cohort as per our analysis of U.S. Census Bureau American Community Survey:
- Fort Collins's population under 18 was 17.53%, compared to the 22.51% nationwide.
- Fort Collins's working population (between 18 and 64) was 71.39%, compared to 61.45% nationwide.
- Fort Collins's elderly or the senior population (over 65 age) was 11.08% as compared to 16.04% nationwide.
Fort Collins, CO population pyramid
Population pyramid for Fort Collins, CO is charted below using the estimates from U.S. Census Bureau's American Community Survey 5-Year estimates. A wide base suggests population increase, narrow base indicates declining birth rates.
Key stats from our analysis of the Fort Collins's population pyramid:
- Youth dependency ratio, which is the number of children aged 0-14 per 100 persons aged 15-64, for Fort Collins, CO, is 19.4.
- Old-age dependency ratio, which is the number of persons aged 65 or over per 100 persons aged 15-64, for Fort Collins, CO, is 14.9.
- Total dependency ratio for Fort Collins, CO is 34.2.
- Potential support ratio, which is the number of youth (working age population) per elderly, for Fort Collins, CO is 6.7.

Here's the Fort Collins, CO's male and female population across different age groups:
Age Group | Population(Male) | Population(Female) | Total Population |
---|---|---|---|
Under 5 years | 3,676 | 3,211 | 6,887 |
5 to 9 years | 4,488 | 3,910 | 8,398 |
10 to 14 years | 4,379 | 4,390 | 8,769 |
15 to 19 years | 7,275 | 7,444 | 14,719 |
20 to 24 years | 13,651 | 13,576 | 27,227 |
25 to 29 years | 9,503 | 8,012 | 17,515 |
30 to 34 years | 7,072 | 5,721 | 12,793 |
35 to 39 years | 5,349 | 4,927 | 10,276 |
40 to 44 years | 4,929 | 4,621 | 9,550 |
45 to 49 years | 4,102 | 3,976 | 8,078 |
50 to 54 years | 3,975 | 3,675 | 7,650 |
55 to 59 years | 4,131 | 4,299 | 8,430 |
60 to 64 years | 3,714 | 4,305 | 8,019 |
65 to 69 years | 3,044 | 3,633 | 6,677 |
70 to 74 years | 2,210 | 2,267 | 4,477 |
75 to 79 years | 1,280 | 1,737 | 3,017 |
80 to 84 years | 730 | 1,223 | 1,953 |
85 years and over | 876 | 1,477 | 2,353 |
Things to know
What is the population of Fort Collins, CO under 18?
Fort Collins's population under the age of 18 is 29,239, as per the latest U.S. Census Bureau's American Community Survey estimates. This population is 17.53% of the total resident population of Fort Collins, CO.
What is the aging population in Fort Collins, CO?
Fort Collins's population aged 65 years and above was 18,477. As per the U.S. Census Bureau's American Community Survey, this population is 11.08% of the entire population.
References
- U.S. Census Bureau American Community Survey (ACS) 2017-2021 5-Year Estimates