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Basic Probability
P(A) = Favorable outcomes / Total outcomes. Example: Rolling a 6 on a die = 1/6
Combinations (nCr)
Number of ways to choose r items from n items where order does not matter.
Permutations (nPr)
Number of ways to arrange r items from n items where order matters.
Multiple Independent Events
P(A AND B) = P(A) × P(B). Enter probabilities as decimals (0 to 1).
At Least One Success
Probability of at least one success in n independent trials.
Odds Converter
Convert between different odds formats.
Probability Calculator
Calculate the likelihood of events and outcomes
What is Probability Calculator?
Probability Calculator helps you figure out the chances of events happening. It handles everything from simple coin flip odds to complex combinations and permutations used in statistics and games.
Why Would You Need to Calculate Probability?
Probability affects decisions in many areas of life:
- Games and lottery: Calculate your actual odds of winning
- Statistics homework: Solve combinations and permutations problems
- Risk assessment: Understand chances of events in business or life
- Sports betting: Convert between odds formats and understand implied probability
- Quality control: Calculate defect probabilities in manufacturing
How to Calculate Probability - Step by Step
- Pick your calculation: Choose from basic probability, combinations, permutations, or odds converter
- Enter your values: Input favorable outcomes, total outcomes, or your n and r values
- Get instant results: See probability as percentage, decimal, fraction, and odds
Key Features
- Basic probability: Calculate simple event chances (like rolling a 6)
- Combinations (nCr): How many ways to choose items when order doesn't matter
- Permutations (nPr): How many arrangements when order does matter
- Multiple events: Find probability when several independent things must happen
- At least one success: Calculate odds of something happening at least once
- Odds converter: Switch between decimal odds, fractional odds, and probability
Tips for Best Results
- Use combinations when you're choosing a group (like lottery numbers)
- Use permutations when order matters (like finishing positions in a race)
- For "at least one" problems, it's often easier to calculate the opposite and subtract from 1
Frequently Asked Questions
What's the difference between combinations and permutations?
Combinations: choosing 3 people for a team (order doesn't matter). Permutations: choosing 1st, 2nd, 3rd place winners (order matters).
How do I calculate lottery odds?
Use the combinations calculator. For picking 6 numbers from 49, enter n=49 and r=6. The result shows your odds of winning.
What are decimal odds vs fractional odds?
Decimal odds of 2.5 mean you get $2.50 for every $1 bet (including your stake). Fractional odds of 3/2 mean you win $3 for every $2 bet (plus your stake back).