Probability Calculators
Last updated: September 2026
Expected Value Calculator
Calculates the expected monetary value of a bet over any number of repetitions, revealing its long-run profitability.
Sports Betting Odds Calculator
Convert American, decimal, or fractional odds into implied probability or potential payout.
Normal Distribution Probability Calculator
Compute the cumulative probability P(X ≤ x) for a normal distribution with a given mean and standard deviation.
Poker Hand Probability Calculator
Calculate the probability of being dealt any classic five-card poker hand from a standard 52-card deck.
Hypergeometric Probability Calculator
Calculate the exact probability of drawing exactly k successes from a finite population without replacement.
Hypothesis Test Calculator
Compute a z-score or t-statistic to determine whether your sample mean differs significantly from a hypothesized population mean.
Coin Flip Probability Calculator
Calculate the exact probability of getting a specific number of heads in a fixed number of fair coin flips.
Hypothesis Testing Calculator
Run a one-sample t-test to decide whether a sample mean differs significantly from a hypothesised population mean.
Poisson Probability Calculator
Computes the probability of observing exactly k events in a fixed interval when events occur at a known average rate.
Geometric Probability Calculator
Find the probability that the first success occurs on exactly the nth trial, given a constant success probability per trial.
Hypergeometric Distribution Calculator
Calculates exact probabilities when drawing items from a finite population without replacement.
Combinations and Permutations Calculator
Calculate combinations (nCr) and permutations (nPr), with or without replacement, for counting and probability problems.
Binomial Probability Calculator
Find the probability of getting exactly k successes, at most k, or at least k in n independent trials.
Lottery Odds Calculator
Find your odds of winning a lottery by computing how many equally likely ticket combinations exist.
Normal Distribution Calculator
Find the cumulative probability P(X ≤ x) for a normal distribution given any mean, standard deviation, and x value.
Dice Roll Probability Calculator
Compute the probability of rolling any target sum with any number of multi-sided dice.
Birthday Paradox Calculator
Find the surprisingly high probability that at least two people in a group share a birthday.
Statistical Power Calculator
Determine the statistical power of a hypothesis test given effect size, sample size, and alpha level.
Sample Size Calculator
Calculate the minimum number of respondents needed to estimate a population proportion within a given margin of error at a chosen confidence level — the standard formula behind almost every survey, poll, and quality audit.
Bayes' Theorem Calculator
Compute the posterior probability P(A|B) using Bayes' theorem.
Conditional Probability Calculator
Apply Bayes' theorem to find conditional probabilities, intersections, and unions of two events.
Chi-Square Goodness of Fit Calculator
Tests whether your observed frequency counts match a theoretically expected distribution.
Multiple Dice Probability Calculator
Calculate the probability that multiple dice produce a specific sum, or a sum greater or less than a target.
Monte Carlo Simulation Calculator
Use repeated random sampling to estimate probabilities for coin flips, dice rolls, or π.
Confidence Interval Calculator
Compute the lower and upper bounds of a confidence interval for a population mean using a sample mean, the standard error of that mean, and a critical z-value (1.645 / 1.96 / 2.576 for 90% / 95% / 99% confidence).
Chi-Square Test Calculator
Compute the chi-square test statistic contribution for one observed-vs-expected category pair using χ² = (observed − expected)² / expected.