Probability Calculator
Calculate probability, odds, and expected value from events and outcomes.
Covers single event, multiple events, and complementary probability.
Probability Result
Basic Probability:
P(event) = Favorable outcomes / Total outcomes
Odds in favor:
Odds = Favorable : Unfavorable
Complementary probability:
P(not A) = 1 - P(A)
Multiple independent events:
- Both occurring:
P(A and B) = P(A) × P(B) - Either occurring:
P(A or B) = P(A) + P(B) - P(A and B) - At least one in n trials:
P = 1 - (1 - P(A))^n
Expected Value:
E = ∑ (value × probability)
For a simple bet: E = (payout × P(win)) - (cost × P(lose))
Examples:
- Coin flip heads: 1/2 = 50%
- Rolling a 6: 1/6 = 16.67%
- Drawing an ace: 4/52 = 7.69%