Probability Calculator - Single & Multiple Events

Use our Probability Calculator to determine the likelihood of single or multiple events. Input values for independent or dependent events. Suitable for students and statisticians. Receive instant results for binomial and conditional probabilities.


Probability Results
Decimal
0
Percentage
0%
Explanation

What is Probability?

Probability is a measure of the likelihood of an event occurring. It is expressed as a number between 0 (impossible) and 1 (certain), or as a percentage between 0% and 100%.

How Are Probabilities Calculated?

Different types of probability calculations: 1. Simple Probability = Favorable Outcomes ÷ Total Possible Outcomes 2. Compound Probability (Independent) = P(A) × P(B) 3. Complement Probability = 1 - P(A)

Common Applications

Statistics

Analyzing data and making predictions

Games

Calculating odds in games of chance

Risk Analysis

Evaluating business and project risks

Science

Predicting experimental outcomes

Tips for Probability Calculations

  • Always express probabilities as decimals between 0 and 1
  • For independent events, multiply individual probabilities
  • Use complement probability for "not happening" scenarios
  • Consider whether events are dependent or independent

Frequently Asked Questions

Simple probability calculates the chance of a single event occurring (favorable outcomes divided by total outcomes). Compound probability calculates the chance of two independent events both occurring by multiplying their individual probabilities together.

Complement probability calculates the chance of an event NOT happening. If an event has probability P, its complement (not happening) is 1 - P. For example, if the probability of rain is 0.3, the probability of no rain is 1 - 0.3 = 0.7 (70%).

Probability of 0 means an event is impossible, and 1 means it is certain to happen. Values between represent the likelihood - 0.5 means equally likely to happen or not. Percentages (0-100%) are just probabilities multiplied by 100 for easier understanding.