Birthday Paradox Calculator

How to Solve The Birthday Paradox

The birthday paradox can be solved with just one variable:

• The number of people in the room

The formula for calculating the percentage is rather complex. That is why it would be best to allow a tool like this one to do the math and work for you.

Understanding Your Results

The result is a percentage that represents the probability of at least two people in the room sharing a birthday. For example, with just 23 people in the room, the chance is approximately 50%.

How to Use the Birthday Paradox Tool

This tool is designed to be simple and easy to use. You can find the answer by following these steps:

1. Enter the number of people in the room.


2. Click the calculate button to get your results instantly.

Calculation Example

For example, to calculate the probability of at least two people sharing a birthday in a college class of 31 students, enter "31" into the input field. You can now hit calculate to get an answer of 73.05% chance of at least two people sharing a birthday.