Birthday paradox
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Chance at least two share a birthday50.73 %
Worked example
Given: People in the room = 23
Result: Chance at least two share a birthday = 50.73 %
How it is calculated
1. Enter the values you know. 2. The calculator converts them to base units and applies the formula. 3. The result is shown in the unit you choose.
Frequently asked questions
How do I calculate it?
Given: People in the room = 23. Result: Chance at least two share a birthday = 50.73 %.
Is the calculator free and private?
Yes. It is free, needs no sign-up and runs in your browser — the numbers you type stay on your device.