Birthday Paradox Calculator
Free calculate the probability of shared birthdays in a group - a counterintuitive probability result.
Birthday Paradox Settings
Birthday Paradox Results
Enter parameters to calculate results
About the Birthday Paradox
The Paradox
- • With 23 people: 50.7% chance
- • With 50 people: 97% chance
- • With 70 people: 99.9% chance
- • Counterintuitive result
Why It Happens
- • Many possible pairs
- • Combinatorial explosion
- • Not about specific dates
- • Any shared birthday counts