Calculate probability as a fraction, decimal, percentage, and odds ratio. Useful for basic statistics, classroom examples, games, and quick chance calculations.
Quick Presets
Fraction
9/10
Odds
9:1
Decimal
0.9000
Probability measures how likely an event is to happen. It is usually expressed as a value between 0 and 1, or as a percentage between 0% and 100%. The closer the number is to 1, the more likely the event.
Divide the number of favorable events by the total number of possible events.
The chance that the event does NOT occur.
Probability compares favorable outcomes with total outcomes, while odds compare favorable outcomes with unfavorable outcomes.
Specially picked tools to help you plan better.