Weird
Shared birthday (23 people)
Odds
~50.7% (about 1 in 2)
group of 23 people · Any (uniform birthday assumption)
What this means
Counterintuitive classic: you only need 23 people for roughly even odds that two share a birthday — not 183.
Methodology
Classic probability result: with 23 people and 365 equally likely birthdays (ignoring leap days), P(at least one shared birthday) ≈ 50.7%. Displayed as ~1 in 2 for compare math.
Updated 2026-01-15
Source
Birthday paradox (exact approximation) ↗Share
Birthday paradox odds: ~50.7% (about 1 in 2) (group of 23 people). — How Likely Is That? https://www.howlikelyisthat.com/odds/birthday-paradox-odds
Compare this event
See how it stacks up against something else — get a shareable “N× more likely” line.