Find a simple probability from favorable and total outcomes, with the percent, complement, and odds. Enter both counts.
Usage Tip
Probability and odds differ: a probability of 1/6 is odds of 1 to 5, not 1 to 6.
complement = 1 − probability
For equally likely outcomes it is just favorable over total.
The complement is the chance the event does not happen.
Odds in favor compare favorable to unfavorable outcomes.
Probability is the number of favorable outcomes divided by the total number of equally likely outcomes, giving a value from 0 to 1 that can also be written as a percent. The complement is the chance the event does not happen, found as one minus the probability. Odds compare favorable outcomes with unfavorable ones instead, so a probability of one in four corresponds to odds of one to three.
This simple formula only works when every outcome is equally likely, such as a fair die or a well shuffled deck. For events that are not equally likely, or that depend on each other, you need a different approach. Favorable outcomes can never exceed the total.