Birthday Problem Calculator
Birthday Problem: a planned Super Calculator tool. Covers group size n. Stub page: the tool, its formula and a worked example are not published yet. Scope is.
Birthday Problem Calculator is a planned calculator in the mathematics section of Super Calculator, covering probability and combinatorics.
What this calculator will compute
Inputs: group size n, number of possible days or values d and target probability (optional).
Outputs: collision probability (%), group size needed for a target probability and probability table.
Formula, recorded as scope and not yet verified against a primary source: P(at least one shared birthday) = 1 - (365! / (365-n)!) / 365^n, computed in log space. Generalizes to any pool size d, giving the collision probability used for hash and identifier analysis: approximately 1 - exp(-n^2/(2d)).
Status
This page is a stub. The calculator is not built, no figure on this page has been verified against the authority that sets it, and nothing here should be used to make a decision. The page exists so that the site structure is complete and so that articles can link this concept on first mention.
The stub carries noindex, nofollow and is excluded from the sitemap.