Probability Calculator

Single-event, complementary, AND, OR, plus coin and dice shortcuts.

Single event probability

A: favourable outcomes out of total

P(A) = — · P(not A) = —

Two independent events

P(A) = P(B) =

P(A and B) = — · P(A or B) = —

Coin flips — getting exactly K heads in N flips

N flips: K heads:

P = —

Dice — sum of two 6-sided dice equals X

Target sum X:

P = — (out of 36)

Notes

The two-events row assumes independence (one outcome doesn't affect the other). Coin flips use the binomial formula C(n,k)·0.5^n. The dice row enumerates the 36 outcomes of two fair 6-sided dice.