The Odds Of Sharing A Birthday

The Odds Of Sharing A Birthday

Most people have difficulty understanding the birthday problem, because they can't wrap their brains around how the number of possible pairs increases exponentially as the number of people increases linearly. In a group of 75 people, there's a 99.9% chance that two will share a birthday.


Key Facts In This Video

  • 1

    There are 23 people on the field during a football/soccer game: 11 per team, plus one referee. (0:23)

  • 2

    For a group of 23 people, the probability that no two people share a birthday is 49.3%; the probability that two people do is 50.7%. (2:40)

  • 3

    A group of 23 people equates to 253 possible pairs of people. (3:30)

See all





Get smarter every day! Like us on Facebook.
You'll get the most interesting and engaging topics in your feed, straight from our team of experts.