How old is someone named Brennan?
The average Brennan is 24 years old.
Half of all living Brennans are between 16 and 30.
When was Brennan popular?
Brennan was a boom name: it shot up, peaked in 2009, and dropped away. That's why most Brennans are close to the same age.
Popular names of 2009 · The most popular names of the 2000s →
Show the numbers by decade
| Born in | Babies born | Alive today |
|---|---|---|
| 1910s | 5 | 0 |
| 1940s | 6 | 0 |
| 1950s | 80 | under 100 |
| 1960s | 394 | 320 |
| 1970s | 1,008 | 910 |
| 1980s | 2,973 | 2,800 |
| 1990s | 8,874 | 8,600 |
| 2000s | 12,394 | 12,000 |
| 2010s | 8,170 | 8,100 |
| 2020s | 1,583 | 1,600 |
How many Brennans are still alive?
About 35,000 Brennans are alive in the US today. That's 97% of the roughly 35,000 babies named Brennan since 1916.
Nearly every Brennan ever born is still alive, because almost all of them are young.
What generation is the name Brennan?
More than half of living Brennans are in Gen Z, born between 1997 and 2012.
- Boomer under 1%
- Gen X 4%
- Millennial 23%
- Gen Z 55%
- Gen Alpha 17%
Is Brennan an old name?
Not really. Brennan is younger than 62 in 100 names on AgeByName.
Looking ahead: if babies keep getting the name at today's pace, the typical Brennan will be 46 in 2056, so the name is getting older.
Is Brennan a boy or girl name?
Mostly a boy's name: 94% of living Brennans are men, and 6% are women.
The women average 24 and the men 24.
Names the same age as Brennan
NAME TWIN
Brennan's name twin is Adrianna. Of all 3,713 names on AgeByName, Adrianna's age curve is the closest match to Brennan's: 93% alike.
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Questions about the name Brennan
How old is the average Brennan?
The average Brennan in the US is 24 years old. The median is 23, so half are older and half younger.
How many people are named Brennan?
About 35,000 Brennans are alive in the US today, out of roughly 35,000 babies given the name since 1916.
When was the name Brennan most popular?
In 2009, when about 1,600 baby boys were named Brennan.
Is Brennan a Gen Z name?
Yes. About 55% of living Brennans are in Gen Z, born between 1997 and 2012.
Estimates from Social Security Administration baby-name records (births 1880–2025) and SSA cohort life tables (2026 Trustees Report). Updated each spring. How we calculate this