Probability Calculator
Calculate the probability of single or multiple events occurring using simple inputs.
Number of outcomes you want to occur
Total number of possible outcomes
Probability Results
📊 Calculation
P(A) = Favorable Outcomes / Total Outcomes
P(A) = 1 / 6
P(A) = 0.1667
Odds: 1:5
🎲 Common Probabilities
💡 Probability Tips
- • Probability ranges from 0 (impossible) to 1 (certain)
- • Multiply independent probabilities for AND events
- • Add probabilities for OR events (subtract overlap)
- • Complement: P(NOT A) = 1 − P(A)
- • Odds ≠ Probability (odds express ratio)
- • More trials converge to theoretical probability
Formula
P(A) = Favorable Outcomes / Total Outcomes
P(A AND B) = P(A) × P(B)
P(A OR B) = P(A) + P(B) − P(A AND B)
How it works
Single Event: P(A) = Favorable Outcomes / Total Outcomes Multiple Events (AND): P(A AND B) = P(A) × P(B) Multiple Events (OR): P(A OR B) = P(A) + P(B) − P(A AND B) Complement: P(NOT A) = 1 − P(A) Likelihood Scale: 0 = Impossible 0.5 = Equally likely 1 = Certain Examples: Fair coin: P(Heads) = 1/2 = 0.5 Fair die: P(rolling 1) = 1/6 ≈ 0.1667 Two dice sum to 7: 6/36 ≈ 0.1667
The probability calculator computes the likelihood of single or multiple events occurring. Enter the number of favorable outcomes and total outcomes, or provide event probabilities. Calculates probability, percentage, complement, and likelihood classification.
Why this matters
Understanding probability is essential for decision-making, risk assessment, and statistics. Probability helps predict outcomes in games, finance, weather, medicine, and everyday situations. Knowing the odds lets you make informed choices based on likelihood.
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The complete guide to probability calculator
Formulas, examples, and tips explained in plain English