Probability Theory And Odds calculators
35 calculators Bayes' Theorem Calculator Calculate any Bayes' theorem probability: posterior P(A|B), reverse-solve for the prior, sensitivity or false-positive rate, plus a live confusion matrix.
Open Combination Calculator (nCr and nPr) Calculate nCr and nPr with or without repetition. See step-by-step formulas, single-draw probability, and all four classical selection modes in one place.
Open Conditional Probability Calculator Calculate P(A|B) three ways: joint probabilities, Bayes formula with P(A) and P(B|A), or raw event counts. Get all four conditional outputs plus an independence test.
Open Dice Probability Calculator Dice probability calculator with 9 modes: exact sum, at-least, at-most, exactly K dice, at-least K, all-same, all-high, all-low, and advantage/disadvantage (D&D).
Open Expected Value Calculator Calculate expected value E[X], variance, and standard deviation of any discrete distribution. Enter outcomes and probabilities, get the full statistical breakdown.
Open Odds Calculator Convert American, decimal, fractional, or ratio odds to implied probability, payout, and profit. Remove the vig to find true fair-odds probability.
Open Relative Risk Calculator Calculate relative risk (RR) with 95% CI, NNT, attributable fraction, odds ratio and p-value from a 2x2 contingency table. Full show-your-work steps included.
Open Accuracy Calculator Calculate accuracy, precision, recall, F1 score, specificity and false-positive rate from a confusion matrix - or use the prevalence or percent-error method.
Open Bertrand's Box Paradox Calculator Solve Bertrand's box paradox with Bayes' theorem. Enter box counts, pick the observed coin, and get the exact probability with a full step-by-step breakdown.
Open Bertrand's Paradox Calculator Explore Bertrand's Paradox: three sampling methods give probabilities of 1/3, 1/2, and 1/4 for a random chord exceeding an inscribed triangle's side.
Open Birthday Paradox Calculator Calculate the probability that at least two people in a group share a birthday. Includes reverse mode, leap year option, pair count, and a full probability table.
Open Boy or Girl Paradox Calculator Solve all three variants of the boy or girl paradox: the classic 1/3 vs 1/2 problem, the Tuesday born-on-a-day variant (13/27), and any named-attribute generalisation.
Open Chebyshev's Theorem Calculator Find what proportion of data lies within k standard deviations of the mean, for any distribution. Reverse-solve for k from a target percentage. Steps shown.
Open Coin Flip Probability Calculator Calculate the probability of getting any number of heads (or tails) in multiple coin flips. Supports exact, at-least, at-most modes and biased coins.
Open Coin Flip Probability Calculator Calculate the probability of any number of heads in N coin flips. Binomial formula, fair or biased coin, exact/at-least/at-most modes, distribution chart.
Open Coin Toss Streak Calculator: Probability of Consecutive Heads or Tails Calculate the probability of getting a streak of consecutive heads or tails in N coin tosses. See expected wait time, step-by-step math, and a probability curve.
Open Confusion Matrix Calculator Enter TP, FP, TN, FN to instantly compute accuracy, precision, recall, F1 score, MCC, specificity, NPV, and 10+ more classification metrics with step-by-step formulas.
Open Dice Average Calculator Find the expected average, standard deviation, min, max, and variance for any dice pool instantly. Supports d4, d6, d8, d10, d12, d20, plus a flat modifier.
Open Dice Probability Calculator Calculate dice probabilities instantly: exact sums, cumulative thresholds, binomial match counts, and a live distribution chart. Covers d4 to d20 and custom dice.
Open False Positive Paradox Calculator Calculate the true probability of a positive test result using Bayes' theorem. Enter prevalence, sensitivity, and specificity to reveal the false positive paradox instantly.
Open Implied Probability Calculator Convert American, decimal, or fractional betting odds to implied probability instantly. Includes vig removal, fair-odds conversion, and value-bet analysis.
Open Lottery Calculator Calculate lottery odds for Powerball, Mega Millions, or custom games. See jackpot probability, expected value per ticket, prize tier breakdown, and lifetime odds.
Open Monty Hall Problem Calculator Calculate the exact probability of winning by switching or staying in the Monty Hall problem. Supports 3 to 10 doors with step-by-step Bayes theorem math.
Open P-Hat Calculator (Sample Proportion) Calculate p-hat (sample proportion) from successes and sample size. Get the standard error, z-score, confidence interval, and normal-approximation check instantly.
Open Parrondo's Paradox Calculator Calculate how two losing games combine to win with Parrondo's Paradox. Set probabilities, pick a strategy, and see expected capital drift and Markov chain analysis.
Open Password Combination Calculator Calculate how many possible password combinations exist for any length and character set. Includes entropy in bits, estimated crack time, and strength rating.
Open Permutation Calculator Calculate permutations (nPr) instantly. Supports standard, with-repetition, and circular modes. Shows the full step-by-step formula and worked example.
Open Post-Test Probability Calculator Calculate post-test probability from prevalence, sensitivity, and specificity. Get PPV, NPV, likelihood ratios, and a full Bayesian breakdown instantly.
Open Probability Calculator Calculate probability for single events, two independent events (intersection, union, complement), or a normal distribution. Instant results with step-by-step working.
Open Probability of 3 Events Calculator Find the probability of all three events, at least one, exactly one, at least two, exactly two, or none. Works for any three independent events.
Open Random Number Generator Generate one or many random integers or decimals in any range. Choose quantity up to 20, allow or block duplicates, sort results, and see a frequency chart.
Open Risk Calculator Calculate relative risk, absolute risk reduction, number needed to treat, odds ratio and 95% confidence intervals from a 2x2 table or raw event rates.
Open Roulette Payout Calculator Calculate your roulette payout for any bet type on European or American wheels. See winning probability, expected value, and house edge instantly.
Open Sensitivity and Specificity Calculator Calculate sensitivity, specificity, PPV, NPV, accuracy and likelihood ratios from your 2x2 contingency table. Adjust prevalence to see how predictive values change.
Open Two Envelopes Paradox Calculator: Expected Value and the Switching Fallacy Enter the amount in your envelope to see the flawed switching argument vs. the correct expected value. Understand the two-envelope paradox with step-by-step math.
Open
No calculators match your filter.