San Diego County, CA population age distribution
A complete breakdown of San Diego 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 | 198,377 | 6.02% |
5 to 9 years | 191,887 | 5.82% |
10 to 14 years | 206,127 | 6.25% |
15 to 19 years | 207,669 | 6.3% |
20 to 24 years | 240,936 | 7.31% |
25 to 29 years | 270,456 | 8.2% |
30 to 34 years | 264,425 | 8.02% |
35 to 39 years | 238,552 | 7.24% |
40 to 44 years | 214,765 | 6.52% |
45 to 49 years | 204,357 | 6.2% |
50 to 54 years | 201,843 | 6.12% |
55 to 59 years | 202,794 | 6.15% |
60 to 64 years | 189,265 | 5.74% |
65 to 69 years | 155,118 | 4.71% |
70 to 74 years | 121,334 | 3.68% |
75 to 79 years | 76,083 | 2.31% |
80 to 84 years | 53,016 | 1.61% |
85 years and over | 59,313 | 1.8% |
TABLE OF CONTENTS
San Diego County, CA population by age group
Sources: U.S. Census Bureau, American Community Survey (ACS) 2021

The largest age group in San Diego County, CA was for the group of age 25-29 years with a population of 270,456 (8.20%), according to the 2021 American Community Survey.
At the same time, the smallest age group in San Diego County, CA was the 80-84 years with a population of 53,016 (1.61%).
San Diego County, CA population by age cohort
To better understand the age distribution of San Diego County, CA'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 | 713,838 | 21.66% |
18 to 64 years | 2,117,615 | 64.24% |
85 years and over | 464,864 | 14.1% |
Key stats for each age cohort as per our analysis of U.S. Census Bureau American Community Survey:
- San Diego County's population under 18 was 21.66%, compared to the 22.51% nationwide.
- San Diego County's working population (between 18 and 64) was 64.24%, compared to 61.45% nationwide.
- San Diego County's elderly or the senior population (over 65 age) was 14.10% as compared to 16.04% nationwide.
San Diego County, CA population pyramid
Population pyramid for San Diego County, CA 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 San Diego County's population pyramid:
- Youth dependency ratio, which is the number of children aged 0-14 per 100 persons aged 15-64, for San Diego County, CA, is 26.7.
- Old-age dependency ratio, which is the number of persons aged 65 or over per 100 persons aged 15-64, for San Diego County, CA, is 20.8.
- Total dependency ratio for San Diego County, CA is 47.5.
- Potential support ratio, which is the number of youth (working age population) per elderly, for San Diego County, CA is 4.8.

Here's the San Diego County, CA's male and female population across different age groups:
Age Group | Population(Male) | Population(Female) | Total Population |
---|---|---|---|
Under 5 years | 101,638 | 96,739 | 198,377 |
5 to 9 years | 98,571 | 93,316 | 191,887 |
10 to 14 years | 105,316 | 100,811 | 206,127 |
15 to 19 years | 108,476 | 99,193 | 207,669 |
20 to 24 years | 133,771 | 107,165 | 240,936 |
25 to 29 years | 141,859 | 128,597 | 270,456 |
30 to 34 years | 137,543 | 126,882 | 264,425 |
35 to 39 years | 122,188 | 116,364 | 238,552 |
40 to 44 years | 111,199 | 103,566 | 214,765 |
45 to 49 years | 103,001 | 101,356 | 204,357 |
50 to 54 years | 101,334 | 100,509 | 201,843 |
55 to 59 years | 100,369 | 102,425 | 202,794 |
60 to 64 years | 93,238 | 96,027 | 189,265 |
65 to 69 years | 73,869 | 81,249 | 155,118 |
70 to 74 years | 56,662 | 64,672 | 121,334 |
75 to 79 years | 33,469 | 42,614 | 76,083 |
80 to 84 years | 22,869 | 30,147 | 53,016 |
85 years and over | 22,792 | 36,521 | 59,313 |
Things to know
What is the population of San Diego County, CA under 18?
San Diego County's population under the age of 18 is 713,838, as per the latest U.S. Census Bureau's American Community Survey estimates. This population is 21.66% of the total resident population of San Diego County, CA.
What is the aging population in San Diego County, CA?
San Diego County's population aged 65 years and above was 464,864. As per the U.S. Census Bureau's American Community Survey, this population is 14.10% of the entire population.
References
- U.S. Census Bureau American Community Survey (ACS) 2017-2021 5-Year Estimates