Probability Calculator

Find a simple probability from favorable and total outcomes, with the percent, complement, and odds. Enter both counts.

Probability
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Favorable over total.

Usage Tip

Probability and odds differ: a probability of 1/6 is odds of 1 to 5, not 1 to 6.

THE MATH
probability = favorable outcomes ÷ total outcomes
complement = 1 − probability
Probability is the chance of an event, from 0 (impossible) to 1 (certain).
For equally likely outcomes it is just favorable over total.
Favorable outcomes must be between 0 and the total.
The complement is the chance the event does not happen.
Odds in favor compare favorable to unfavorable outcomes.
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