How Many People Are Named Brennan?
An estimated 34,525 people in the United States have the first name Brennan. It is predominantly male (93.7%). The average bearer is 24 years old, and Brennan peaked in popularity in 2009 with 1,550 births that year.
Below you will find a full statistical profile of Brennan as a first name in the United States, including gender data, a year-by-year popularity timeline going back to 1880, a decade breakdown, state-by-state birth registrations, and, when available, a 2020 Census snapshot showing who had the name at that point in time. You can also check how many people share the full name Brennan paired with any surname.
Estimated Living Americans
34,525
About 1 in 9,928 people in the U.S.
Rarity
Uncommon
Predicted Gender
Male
93.7% confidence
Average Age
24
years old
Peak Year
2009
1,550 births
Total Registered
35,250
since 1880
Gender Distribution for Brennan
Brennan is predominantly male (93.7%), though 2,218 female births have been registered. It functions as a unisex name for a small percentage of bearers.
Brennan as a male name
Ranked #1,054 in 2024
207 male births in 2024
Peak: 2009 (1,464 births)
Brennan as a female name
Ranked #6,414 in 2024
18 female births in 2024
Peak: 2007 (100 births)
Brennan in the 2020 Census
The 2020 Census recorded 31,223 people with the first name Brennan, which placed it at #1,225 in the published first-name tables. This is a snapshot of people who already had the name in 2020. The estimated living count elsewhere on this page is different: it is a current estimate built from SSA birth records and age-based survival rates, so the two figures are not expected to match exactly.
Read this section as a snapshot of people who already had the name in 2020. The SSA charts elsewhere on this page are still the better way to see how the name rose, fell, or shifted across generations.
Gender in the 2020 Census
In the 2020 Census, Brennan was recorded as predominantly male. Out of 31,223 people with this name in that snapshot, 93.8% were male and 6.2% were female. That is very close to the long-run birth pattern in SSA records, where the name is male 93.7% of the time.
Census Count
31,223
people with this name
Census Rank
#1,225
among Census first names
Frequency Rate
10.34
per 100,000 people
Recorded Race and Hispanic Origin in the 2020 Census
In the 2020 Census, the first name Brennan was most commonly recorded among people who identified as White (81.95%). The next largest recorded groups were Two or More Races (5.61%) and Hispanic (5.53%).
These percentages describe the people who had the first name Brennan in the 2020 Census. They do not tell you the deeper meaning or origin of the name itself.
2020 Census demographic breakdown
Each row shows a recorded Census category for people with the first name Brennan.
| Group | Share | Count |
|---|---|---|
| White | 81.95% | 25,591 |
| Two or More Races | 5.61% | 1,752 |
| Hispanic | 5.53% | 1,726 |
| Black | 4.61% | 1,438 |
| Asian and Pacific Islander | 1.58% | 493 |
| American Indian and Alaska Native | 0.72% | 226 |
The Census published separate sex and race/origin tables for first names, so their total counts can differ slightly for the same name. That is why the race section focuses on the demographic mix rather than repeating a second headline count.
Brennan: Popularity Over Time
SSA records for Brennan span from the 1910s to the 2020s, covering 10 decades of naming data. The most popular decade for this name was the 2000s, when 12,394 babies were registered. Brennan has declined significantly from its peak in the 2000s. Recent registrations are a fraction of what they were at the name's height.
Brennan by Decade
How has Brennan tracked across different eras? The table below groups all SSA birth registrations into 10-year periods, with separate male and female counts. The colored bar shows each decade's share relative to the peak.
Brennan by State
Birth registrations for Brennan span all 50 states and territories in the SSA database. The highest counts are in California, Texas, Louisiana. The lowest are in District of Columbia, Vermont, Delaware. On average, about 619 Brennans were registered per state.
Brennan + Last Name Combinations
How many people share a full name with Brennan as the first name? Click a combination below to see the estimate, or search any pairing.
Names Similar to Brennan
Other first names starting with B with a similar number of bearers.
Brennan: Questions and Answers
How many people in the U.S. are named Brennan?
We estimate approximately 34,525 people named Brennan are alive in the United States today. This is based on SSA birth records from 1880 to 2024, adjusted for mortality using CDC life tables. About 1 in 9,928 Americans share this first name.
Is Brennan a common name?
Brennan is classified as "Uncommon" and is more popular than 98.9% of all first names in the SSA database. A total of 35,250 births have been registered with this name since 1880.
When was Brennan most popular?
Brennan reached peak popularity in 2009, when 1,550 babies were given this name. The average age of a living person named Brennan is approximately 24 years old, reflecting when the name was most commonly given.
How common was Brennan in the 2020 Census?
The 2020 Census recorded 31,223 people with the first name Brennan. That placed it at #1,225 in the published Census first-name tables, or 10.34 people per 100,000.
Why is the Census count different from the living estimate?
Because they measure different things. The Census number is a count of people with the name in 2020. The living estimate is a current model based on SSA birth records and survival rates, so it aims to estimate how many people with the name are alive now.
What does the SSA popularity chart show?
The popularity chart tracks birth registrations, not people currently alive. It shows how often Brennan was given to babies from 1880 through 2024, which is why it is the best tool on the page for seeing long-run naming trends.
What does the Census say about the gender split for Brennan?
In the 2020 Census snapshot, Brennan was recorded as predominantly male. The published split was 93.8% male and 6.2% female.
What does the Census say about the background of people named Brennan?
In the 2020 Census, the first name Brennan was most commonly recorded among people who identified as White (81.95%). The next largest recorded groups were Two or More Races (5.61%) and Hispanic (5.53%). These percentages describe the people who had the name in the 2020 Census, not the deeper meaning or origin of the name itself.
Why can the Census sex total and race total differ slightly?
The Census published separate first-name tables for sex and for race and Hispanic origin. Those totals can differ slightly for the same name, so the page uses them as two related snapshots rather than treating them as perfectly interchangeable counts.
Does every first name have Census demographic data?
No. The public Census first-name tables only include names that met the Bureau's publication rules. That means some names on this site will have SSA history but no published Census demographic snapshot.
Is Brennan a male name?
Brennan is predominantly male. 93.7% of people with this name are male. See the gender breakdown above for full details.
Why can Brennan have a lot of living bearers even if it is not trendy now?
Because a name can build up a large population over many decades. Brennan peaked in 2009, and the average living bearer is about 24 years old, so a name can still have millions of living bearers even after it stops feeling current for newborns.
How many Brennan Smiths are there?
To find how many people share a specific full name, we combine first name and surname frequencies. Try: Brennan Smith, Brennan Johnson, Brennan Williams. You can also search any combination on our homepage.
Where does this data come from?
Our estimates use Social Security Administration birth records (1880 to 2024), adjusted for survival using CDC 2023 life tables broken down by sex. The U.S. population figure (342,754,338) is from the Census Bureau's July 2025 estimate. Full methodology.
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