Do you know someone who has the same birthday as you?
According to the “birthday paradox,” in a random group of 23 people, there is about a 50% chance two people will share a birthday. Any more than that, and it gets increasingly likely that a pair of matching birthdays exist.
According to birth data from the Centers for Disease Control and Prevention and the Social Security Administration, here are the most popular days to blow out the candles in the United States.
The most common birthday is Sept. 9. In second and third place are Sept. 19 and 12.
In fact, the entire top 10 list is made of September birthdays between Sept. 9 and 20. Count backward and you’re just in time for the holidays, since pregnancy is an average of 40 weeks from last menstruation.
Why the holidays? Perhaps because there’s more holiday cheer in the air, and it could have something to do with the fact that many people have free time on vacation days they take around Christmas and New Year’s, to celebrate with family and friends. There’s also the general sense of romance around the holidays — December is the most popular month to get engaged. One study even found a 9.1% peak in conception at the end of the year.
Scroll down to check out the full list of birthdays from most to least common.
If you were born on the most popular day of the year, here are a few celebs you share a birthday with:
It’s Sagittarius season:Check out these 30 celebrity fire signs
Though September dominates the top ten most common birthdays, August is actually the most common birth month.
According to the birth data, there were just under 7,600,000 births in August between 1994 and 2014. The second most common birth month is July, with 7,500,795 births and September in third place with 7,411,299. It’s worth noting, though, that both July and August have 31 days in the month while September only has 30. The least common birth month is predictably February, which only has 28 days.
Birth months of the year, in order of most common to least common:
The least common birthday is leap day, or February 29. But because the day only occurs once every four years, it’s obvious it would yield the least amount of birthdays.
The rarest birthday of the 365 annual calendar days is Christmas Day, Dec. 25.
If your birthday is New Year’s Day or Christmas Eve, you also have uncommon birthdays. Jan. 1 and Dec. 24 are just below Christmas on the list.
Late November birthdays are also pretty rare as Thanksgiving celebrations ramp up in the United States. Nov. 23-28 all fall between 354 and 360 out of the 365 calendar days. And July 4th, which occurs in the second most popular birth month, is 363rd on the list.
According to a working paper from the National Bureau of Economic Research, there are 18% less births on the day of and just after a holiday. Around half of the decline is due to fewer cesarean sections scheduled on holidays, in part because of low hospital staffing numbers on the holiday and cultural attitudes — parents’ desires to separate fixed holidays and birthdays.
If you’re a Christmas baby born in Capricorn season, here are the famous figures you share a birthday with:
Birthday freebies:Score these items from your favorite stores
USA TODAY is exploring the questions you and others ask every day. From “How much do Amazon drivers make?” to “What is my love language?” to “Is Chipotle healthy?”, we’re striving to find answers to the most common questions you ask every day. Head to our Just Curious section to see what else we can answer for you.
