probability Calculators
Last updated: May 2026
Coin Flip Probability Calculator
Calculate the exact probability of getting a specific number of heads in a fixed number of fair coin flips.
Dice Roll Probability Calculator
Compute the probability of rolling any target sum with any number of multi-sided dice.
Lottery Odds Calculator
Find your odds of winning a lottery by computing how many equally likely ticket combinations exist.
Poker Hand Probability Calculator
Calculate the probability of being dealt any classic five-card poker hand from a standard 52-card deck.
Birthday Paradox Calculator
Find the surprisingly high probability that at least two people in a group share a birthday.
Bayes' Theorem Calculator
Compute the posterior probability P(A|B) using Bayes' theorem.
Hypergeometric Probability Calculator
Calculate the exact probability of drawing exactly k successes from a finite population without replacement.
Poisson Probability Calculator
Find the probability that exactly k events occur in a fixed interval, given a known average rate λ.
Normal Distribution Probability Calculator
Compute the cumulative probability P(X ≤ x) for a normal distribution with a given mean and standard deviation.
Geometric Probability Calculator
Find the probability that the first success occurs on exactly the nth trial, given a constant success probability per trial.
Binomial Probability Calculator
Find the probability of getting exactly k successes, at most k, or more than k in n independent trials.
Normal Distribution Calculator
Compute left-tail, right-tail, or two-tail probabilities for any normal distribution given its mean and standard deviation.
Multiple Dice Probability Calculator
Calculate the probability that multiple dice produce a specific sum, or a sum greater or less than a target.
Lottery Odds Calculator
Compute your exact odds of winning a lottery jackpot based on pool size, numbers drawn, and bonus ball rules.
Conditional Probability Calculator
Apply Bayes' theorem to find conditional probabilities, intersections, and unions of two events.
Sports Betting Odds Calculator
Convert American, decimal, or fractional odds into implied probability or potential payout.
Birthday Paradox Calculator
Calculate the probability that at least two people in a group share a birthday.
Hypothesis Testing Calculator
Run a one-sample t-test to decide whether a sample mean differs significantly from a hypothesised population mean.
Monte Carlo Simulation Calculator
Use repeated random sampling to estimate probabilities for coin flips, dice rolls, or π.
Bayes' Theorem Calculator
Compute the posterior probability P(A|B) from a prior belief, a likelihood, and a false-positive rate.
Hypergeometric Distribution Calculator
Calculates exact probabilities when drawing items from a finite population without replacement.
Confidence Interval Calculator
Computes the range of values likely to contain a true population mean at your chosen confidence level.
Statistical Power Calculator
Calculates the statistical power of a hypothesis test or the sample size needed to detect a given effect.
Chi-Square Goodness of Fit Calculator
Tests whether your observed frequency counts match a theoretically expected distribution.
Poisson Probability Calculator
Computes the probability of observing exactly k events in a fixed interval when events occur at a known average rate.
Expected Value Calculator
Compute the expected value (mean) of a discrete probability distribution by entering up to three outcomes and their probabilities.
Chi-Square Test Calculator
Calculate the chi-square (χ²) test statistic and compare it against a critical value to test goodness of fit or independence.
Hypothesis Test Calculator
Run a one-sample z-test or t-test to determine whether a sample mean significantly differs from a hypothesized population mean.
Combinations and Permutations Calculator
Calculate combinations (nCr) and permutations (nPr), with or without replacement, for counting and probability problems.
Sample Size Calculator
Determine the minimum sample size needed for a survey or experiment given your confidence level, margin of error, and population size.