What is the most common birthday?
September 9 is the most common birthday in the US: 12,344 births in an average year, in national data from 1994 to 2014. December 25 is the least common everyday date, and February 29 is the rarest of all.
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September 9 is the most common birthday in the US. Across 21 years of national birth records, 1994 to 2014, an average of 12,344 babies a year were born on it, and nine of the ten busiest dates are in September. The quietest dates are holidays. Christmas Day comes last, with barely half as many.
Below: the top and bottom 10, why September wins, the busiest month (it depends how you count), how many people share your birthday, and the cake card we tested on a man who doesn't exist.
Cards made from your photos
The most and least common birthdays in the US
We averaged every calendar date over 21 years of US births: CDC counts for 1994 to 1999 and Social Security counts for 2000 to 2014, as compiled by FiveThirtyEight (github.com/fivethirtyeight/data/tree/master/births). Each number is the births on that date in an average year. One date crashes the September party: July 7, at number seven.
February 29 is left out because it only exists every fourth year. In the leap years it does exist, it gets about 10,500 births, which would put it in the bottom 20 anyway. Spread over four years, it's the rarest birthday by a mile, and it's the only date whose golden birthday never lands on the calendar.
| Rank | Most common | Births | Least common | Births |
|---|---|---|---|---|
| 1 | September 9 | 12,344 | December 25 | 6,601 |
| 2 | September 19 | 12,285 | January 1 | 7,827 |
| 3 | September 12 | 12,282 | December 24 | 8,103 |
| 4 | September 17 | 12,201 | July 4 | 8,825 |
| 5 | September 10 | 12,190 | January 2 | 9,356 |
| 6 | September 20 | 12,162 | December 26 | 9,599 |
| 7 | July 7 | 12,147 | November 27 | 9,770 |
| 8 | September 15 | 12,126 | November 23 | 9,919 |
| 9 | September 16 | 12,114 | November 25 | 10,001 |
| 10 | September 18 | 12,112 | October 31 | 10,030 |
Why is September 9 the most common birthday?
Count back 38 weeks from mid-September and you land in mid-to-late December. September 9 points to about December 17. We'll leave the rest to you.
The quiet dates have a less romantic explanation: scheduling. Lots of births are planned, through inductions and C-sections, and few people plan one for Christmas morning, New Year's Day, the Fourth of July or Thanksgiving week.
The same data shows it every week: an average Tuesday had 12,842 births and an average Sunday had 7,635. Babies don't know what day it is. Hospital calendars do.
Dates people like get a bump too. The single busiest day in the whole data set was Wednesday, September 9, 2009, 09/09/09, with 16,081 births. The quietest was Christmas Day 2011, with 5,728.
What is the most popular birthday month?
It depends how you count. By total births, August wins, with about 363,000 a year in the 1994 to 2014 data, then July, then September. By births per day, September wins at 11,811 a day, because it packs nearly as many babies into 30 days as August does into 31.
At the other end, February has the fewest births, mostly because it's short. Per day, January is the slowest month, at about 10,700. Most late-January dates sit in the bottom quarter of the whole list.
How many people share my birthday?
On an average date, about 1 in 365 people. The US has about 341.8 million people, according to the Census Bureau's July 2025 estimate (census.gov/newsroom/press-releases/2026/population-growth-slows.html), so roughly 936,000 Americans share any given birthday. A mid-September birthday probably shares with closer to a million, and Christmas Day with something like 550,000. Worldwide, it's around 22 million each.
Want a smaller, stranger number? In a room of just 23 people there's a better than even chance that two of them share a birthday. That's the birthday paradox, and it surprises nearly everyone.
And if you know someone born on one of the quiet dates, they've probably had a lifetime of combined presents. Christmas birthday wishes are written for them.
How we made the Cake face card
Whatever the date, the cake is the constant, so one of our cards skips the candles and goes straight in. Cake face puts the birthday person's face popping out of the top of a giant frosted cake, frosting on the nose and eyebrows, guests laughing behind. It's also the card at the top of our Christmas birthday page, for the people born on the rarest everyday date.
We tested it on Dave, 38, from our made-up test family: ginger beard, freckles, receding hairline, does not exist. Dave has face-planted into a birthday cake more than 60 times, every one of them a test. Each take is graded on whether it still looks like him, whether it's funny, whether it fits the card and whether it's well made.
The classic miss: the face-plant happened and the cake didn't notice. Frosting on his face, cake untouched, candles still lit. If you went in face first, the cake has to show it. Another take gave Dave a thick head of dark hair and scored 3 out of 10. The hairline is part of Dave.
Pick a message on the birthday wishes page, add one clear photo, and your words go on the card under the picture. The frosting is our department.
How it works
- Pick a cardPilots, mermaids, rock stars, one very surprised cake. Every one shows a real example first.
- Add their photosOne clear face each, up to 5 people. A selfie is fine. No sign-up.
- Preview it, then payOne picture of them in the card in about 10 seconds. Like it? Apple Pay or Google Pay, and four pictures arrive about 20 seconds later, the video in about 90.
Is 12-12-12 a rare birthday?
No, it was a crowded one. December 12, 2012 had 14,667 US births, about a fifth more than the days on either side, a sign that plenty of parents picked the date on purpose.
What is the most common birthday in the UK?
September 26, in England and Wales. The Office for National Statistics found it was the most common birthday from 1995 to 2014, with about 2,000 births on an average September 26 against roughly 1,800 on a typical day.
Which birthday is the least common?
Leap day, February 29, because it only comes once every four years. If you only count dates that happen every year, Christmas Day is the least common in the US.
By HiWith (Winding AI, Inc.) · support@winding.ai · Updated