Birthday Paradox Simulator
Calculate exact shared-birthday probability and watch repeated classes converge.
Exact probability
Ready
At least one shared birthday.
- Simulated probability
- Not run
- Pairs compared
- 253
- Trials completed
- Not run
The pair count grows as n(n - 1) / 2.
Run the simulation to fill Monte Carlo metrics and convergence.
| Trial | Matching trials | Simulated probability |
|---|
P(match) = 1 - product((days - i) / days), i = 0..people - 1
How?
How this is calculated
The exact calculation multiplies the probability that each new person has a birthday not already seen, then takes the complement. The simulation assigns random day numbers and records whether any birthday repeats.
Formula: P(match) = 1 - product((days - i) / days), i = 0..people - 1
Sources
- Wolfram MathWorld Birthday Problem. Wolfram MathWorld. Retrieved .
Method last reviewed