Probability Calculator

Key Features

• Covers basic probability, permutation/combination, conditional probability, Bayes theorem, binomial distribution, and normal distribution.
• Shows both numeric results and core formulas for learning and quick verification.
• Runs fully in the browser with no input upload.

How to Use

• Basic probability: enter favorable and total outcomes to get P(A), percent, and reduced fraction.
• Permutation/combination: enter n and r, then calculate P(n,r) or C(n,r).
• Conditional and Bayes: provide known probabilities to get intersection and posterior probability.
• Binomial: enter n, p, and k to compute P(X=k), expected value, and variance.
• Normal: enter mean, standard deviation, and x to get density, cumulative probability, and Z-score.

Use Cases

• Statistics practice, formula checks, and exam preparation.
• Experiment analysis, sampling review, and probability-based risk estimation.
• Fast parameter validation during data analysis and modeling.

Notes

• Probability inputs should be between 0 and 1.
• For performance, keep counting parameter n within 50,000.
• Use this tool as a quick aid, and validate critical decisions with domain methods.