Birthday Paradox Calculator: Unraveling Shared Birthday Probabilities

Calculate Shared Birthday Probability

Enter the total number of individuals in your group.

Calculation Results

With people in a group, the probability of at least two sharing a birthday is approximately:

(Assumes 365 days in a year, ignoring leap years.)

Explore the fascinating Birthday Paradox with our intuitive calculator. Quickly determine the surprisingly high probability of shared birthdays within a group of people, a key concept in probability theory. Simply input the number of individuals to see the odds instantly.

Formula:

The probability P(n) that at least two people in a group of n individuals share a birthday is given by:

P(n) = 1 - ∏k=0n-1 ( (365 - k) / 365 )

Where:

  • n: The number of people in the group.
  • 365: The number of days in a year (ignoring leap years).
  • : Denotes the product of the terms from k=0 to n-1.

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