Examples
Examples
Try the starting example
- People
- 23
- Equally likely birthdays
- 365
- Shared birthday probability
- 0.507297
Try another scenario
- People
- 24
- Equally likely birthdays
- 365
- Shared birthday probability
- 0.538344
Calculation method
Calculation method
Shared birthday probability
sharedBirthday(a,b)
Symbols and units
- a
- People
- b
- Equally likely birthdays
Use the units shown. A list keeps the order in which you enter its values. The symbol ^ means “raised to the power of”.
Calculation steps and notation
For n independent people and d equally likely days, probability = 1 − product of (1−i/d) for i from 0 through n−1. Return 1 if n exceeds d.
Assumptions & limits
Assumptions & limits
- Assumes independent, uniformly distributed birthdays and ignores leap-day differences.
Are these inputs private?
These calculations run in your browser. A shared link contains the values you choose to share. Only questions submitted to the separate AI finder are sent to OpenAI.
Further reading
Background reading; this does not imply endorsement or independent review of SumFizz.