Why use this calculator
Probability calculations are fundamental to decision-making, risk assessment, gambling analysis, and scientific research.
How to use it
Enter the number of favorable outcomes and total possible outcomes. The calculator shows probability in multiple formats.
The formula
P(A) = Favorable Outcomes / Total Outcomes. Odds = Favorable / Unfavorable. Complement = 1 - P(A).
Worked examples
3 favorable outcomes out of 10 total
30% probability, 3:7 odds
When people use it
- Risk assessment
- Game theory
- Insurance calculations
- Research design
Tips
- Probability is always between 0 and 1
- Independent events multiply: P(A and B) = P(A) × P(B)
- Mutually exclusive events add: P(A or B) = P(A) + P(B)
Questions people ask
- What's the difference between probability and odds?
- Probability is favorable/total (e.g., 3/10 = 0.3). Odds are favorable/unfavorable (e.g., 3:7). They express the same concept differently.