Probability Calculator: The Complete Guide
Work out the chance of an event. Enter the number of favorable outcomes and the total possible to get the probability as a percentage, a fraction, and odds — and the chance of it happening across several independent tries.
Who the Probability Calculator is for
Students and decision-makers estimating the likelihood of an event or repeated events.
How to use the Probability Calculator
- Type your values into the fields above — pick your currency or units where the calculator offers them.
- Results update automatically as you type; there's no submit button and nothing is sent to a server.
- Adjust any input to compare scenarios, then copy the result with a single click.
How it works
Probability = favorable outcomes ÷ total outcomes. For several independent repeats all succeeding, raise the probability to the power of the number of repeats.
Features
- Probability %
- Fraction and odds
- Repeated-trial chance
- Instant result
Understanding probability
Probability measures how likely an event is, from 0 (impossible) to 1 (certain), and is often shown as a percentage. Dividing favorable outcomes by total outcomes gives the chance of a single event; for independent repeats, multiply the probabilities — which the calculator does via a power.