Loudoun County, VA population age distribution
A complete breakdown of Loudoun County'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 | 27,970 | 6.76% |
5 to 9 years | 32,902 | 7.96% |
10 to 14 years | 34,695 | 8.39% |
15 to 19 years | 29,919 | 7.23% |
20 to 24 years | 21,284 | 5.15% |
25 to 29 years | 20,166 | 4.88% |
30 to 34 years | 27,175 | 6.57% |
35 to 39 years | 34,143 | 8.26% |
40 to 44 years | 36,573 | 8.84% |
45 to 49 years | 34,759 | 8.4% |
50 to 54 years | 30,662 | 7.41% |
55 to 59 years | 25,173 | 6.09% |
60 to 64 years | 19,020 | 4.6% |
65 to 69 years | 13,266 | 3.21% |
70 to 74 years | 10,401 | 2.51% |
75 to 79 years | 6,298 | 1.52% |
80 to 84 years | 4,726 | 1.14% |
85 years and over | 4,442 | 1.07% |
TABLE OF CONTENTS
Loudoun County, VA population by age group
Sources: U.S. Census Bureau, American Community Survey (ACS) 2021

The largest age group in Loudoun County, VA was for the group of age 40-44 years with a population of 36,573 (8.84%), according to the 2021 American Community Survey.
At the same time, the smallest age group in Loudoun County, VA was the 85+ years with a population of 4,442 (1.07%).
Loudoun County, VA population by age cohort
To better understand the age distribution of Loudoun County, VA'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 | 115,705 | 27.98% |
18 to 64 years | 258,736 | 62.56% |
85 years and over | 39,133 | 9.46% |
Key stats for each age cohort as per our analysis of U.S. Census Bureau American Community Survey:
- Loudoun County's population under 18 was 27.98%, compared to the 22.51% nationwide.
- Loudoun County's working population (between 18 and 64) was 62.56%, compared to 61.45% nationwide.
- Loudoun County's elderly or the senior population (over 65 age) was 9.46% as compared to 16.04% nationwide.
Loudoun County, VA population pyramid
Population pyramid for Loudoun County, VA 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 Loudoun County's population pyramid:
- Youth dependency ratio, which is the number of children aged 0-14 per 100 persons aged 15-64, for Loudoun County, VA, is 34.3.
- Old-age dependency ratio, which is the number of persons aged 65 or over per 100 persons aged 15-64, for Loudoun County, VA, is 14.0.
- Total dependency ratio for Loudoun County, VA is 48.3.
- Potential support ratio, which is the number of youth (working age population) per elderly, for Loudoun County, VA is 7.1.

Here's the Loudoun County, VA's male and female population across different age groups:
Age Group | Population(Male) | Population(Female) | Total Population |
---|---|---|---|
Under 5 years | 14,193 | 13,777 | 27,970 |
5 to 9 years | 16,477 | 16,425 | 32,902 |
10 to 14 years | 18,167 | 16,528 | 34,695 |
15 to 19 years | 15,225 | 14,694 | 29,919 |
20 to 24 years | 10,730 | 10,554 | 21,284 |
25 to 29 years | 10,043 | 10,123 | 20,166 |
30 to 34 years | 12,941 | 14,234 | 27,175 |
35 to 39 years | 16,044 | 18,099 | 34,143 |
40 to 44 years | 18,889 | 17,684 | 36,573 |
45 to 49 years | 17,967 | 16,792 | 34,759 |
50 to 54 years | 15,668 | 14,994 | 30,662 |
55 to 59 years | 13,341 | 11,832 | 25,173 |
60 to 64 years | 9,245 | 9,775 | 19,020 |
65 to 69 years | 6,265 | 7,001 | 13,266 |
70 to 74 years | 4,913 | 5,488 | 10,401 |
75 to 79 years | 2,522 | 3,776 | 6,298 |
80 to 84 years | 2,007 | 2,719 | 4,726 |
85 years and over | 1,989 | 2,453 | 4,442 |
Things to know
What is the population of Loudoun County, VA under 18?
Loudoun County's population under the age of 18 is 115,705, as per the latest U.S. Census Bureau's American Community Survey estimates. This population is 27.98% of the total resident population of Loudoun County, VA.
What is the aging population in Loudoun County, VA?
Loudoun County's population aged 65 years and above was 39,133. As per the U.S. Census Bureau's American Community Survey, this population is 9.46% of the entire population.
References
- U.S. Census Bureau American Community Survey (ACS) 2017-2021 5-Year Estimates