🎂 Birthday Paradox Visualiser
Watch birthday collisions happen faster than you'd expect
Simulation Mode
Run thousands of trials to see how the observed probability converges to the theoretical value.
About the Birthday Paradox
The Birthday Paradox is a fascinating probability phenomenon that demonstrates how our intuition about randomness can be misleading. It shows that in a group of just 23 people, there's approximately a 50% chance that two people share the same birthday!
This seems counterintuitive because we often think about the probability of someone sharing our specific birthday. But the paradox is about any two people in the group sharing a birthday, which creates many more possible pairs to compare.
With 23 people, there are 253 possible pairs of people. Each pair has a 1/365 chance of sharing a birthday, and when you combine all these possibilities, the probability of at least one match becomes surprisingly high!