Birthday Math
★ Fun facts for all 366 birthdays

Let's do some birthday math

Discover your half birthday, golden birthday, the weekday you were born and your famous birthday twins.

Or peek at today, November 12 September 9 December 25 February 29

JanFebMarAprMayJunJulAugSepOctNovDec
Hover a line 366 birthdays in one ring
A year of birthdays

Every birthday, in one ring

Each little line is one day, starting with January 1 at the top. The longer and pinker the line, the more babies are born that day. TapClick any line to open its page.

  • The late-summer bulgeJuly to September is packed, peaking on September 9.
  • The Christmas gapLook just before the top: December 24 to 26 nearly vanish.
  • The New Year's Day dipRight at the top of the ring, January 1 is one of the emptiest birthdays of all.

Today, November 12

Happy birthday to

Born today, November 12

The famous people blowing out candles today. See the full list →

  1. Ryan Gosling
    Ryan GoslingCanadian actorFilm & TVTurns 46 today!
  2. Neil Young
    Neil YoungCanadian singer, songwriter and filmmakerMusicTurns 81 today!
  3. Grace Kelly
    Grace KellyAmerican actress and Princess consort of MonacoFilm & TV1929 to 1982
  4. Megan Mullally
    Megan MullallyAmerican actressFilm & TVTurns 68 today!
  5. Wallace Shawn
    Wallace ShawnAmerican actor and playwrightFilm & TVTurns 83 today!
  6. Gustaf Skarsgård
    Gustaf SkarsgårdSwedish actorFilm & TVTurns 46 today!
TapClick any day

How crowded is your birthday?

Every square is one day of the year. Pink days are packed with birthdays, blue days are quiet. TapClick one to open its page.

JanFebMarAprMayJunJulAugSepOctNovDec
Quiet PackedAverage births per day, from 85.7 million U.S. birth records (1994 to 2014)
12,344

babies born in the U.S. on an average September 9, the busiest birthday of the year. Count back nine months and you land on the holidays. Make of that what you will.

6,601

on Christmas Day, the quietest. Hardly anyone schedules a delivery for Christmas, and it shows.

1 in 1,461

days is a February 29. Leap-day babies are rare because the day is rare, not because it's unpopular.

Weird but true
68%

more babies are born in the U.S. on a Tuesday than on a Sunday

The month barely matters: September only beats January by about 10%. The day of the week matters a lot, because most planned deliveries happen Monday to Friday.

More birthday math

Little tools, big answers

Half birthday calculator

The date six months after your birthday, and what happens if you were born on August 31.

Find mine →

Golden birthdays

The year your age matches the day you were born. Coming soon.

Most common birthdays

All 366 birthdays ranked in 21 countries, and why September is so crowded.

See the ranking →