How it works
Calculate the probability of an event as a fraction, percentage, and odds.
Enter the number of favorable outcomes and the total possible outcomes. The calculator returns the probability (0–1), the percent chance, and the favorable:unfavorable odds.
Formula
P = favorable ÷ total; percent = P × 100; odds = favorable : (total − favorable).
f- Favorable outcomes
n- Total outcomes
P- Probability (0–1)
Examples
- 4-sided roll landing on one faceFavorable 1 · total 4Probability 0.25 · 25% · odds 1 : 3
Frequently asked questions
What assumptions are made?
All outcomes are assumed equally likely. Unequal weighting needs a different model.
Can the probability exceed 1?
No — favorable outcomes cannot exceed total outcomes; 1 means certainty.
How to read the result
A probability of 0 means impossible and 1 means certain; values in between express likelihood.
Limitations
Classical (equally likely) probability only; no conditional or Bayesian terms.
Source: Classical definition of probability (favorable / total).