Statistics

Most used

• P-Value CalculatorTurn a z, t, chi-square or F statistic into a p-value, one-tailed or two-tailed.
• T-Score CalculatorConvert a raw score or a z-score into a T-score on the standard scale with mean 50 and standard deviation 10.

All, A–Z

• 37 Percent Rule CalculatorYour chance of picking the best option under the 37 % stopping rule, by time window or by number of candidates.
• Average CalculatorPaste a list of numbers to calculate the average, median, sum, count, minimum and maximum. Choose decimal points or commas and see worked examples.
• Bayes' Theorem CalculatorThe posterior probability P(A|B) from a prior and the true- and false-positive rates.
• Binomial Probability CalculatorThe chance of exactly k successes in n independent trials, each with the same success probability p.
• Coefficient of Variation CalculatorThe coefficient of variation from a mean and a standard deviation — the spread of the data as a percentage of its average.
• Combinations CalculatorHow many ways to choose r items from n when the order of the picks does not matter.
• Combinations with Repetition CalculatorHow many ways to pick r items from n types when the same type may be taken more than once.
• Conditional Probability CalculatorP(A given B) from the joint probability and the probability of B — the chance of A once B is known to have happened.
• Confidence Interval CalculatorEnter a sample mean, known population standard deviation, sample size and z value to get both limits of a two-sided confidence interval.
• Geometric Distribution CalculatorThe chance that the first success lands exactly on trial k, from the per-trial success probability p.
• Margin of Error CalculatorThe margin of error for a proportion from the sample share, the sample size and a confidence multiplier.
• Odds Ratio CalculatorThe odds ratio from a 2×2 contingency table — how the odds of an outcome compare between an exposed and an unexposed group.
• Odds to Probability CalculatorTurn odds of a to b in favour into a probability: a out of the a + b chances there are in total.
• Permutations CalculatorHow many ways to arrange r items chosen from n when the order of the picks matters.
• Permutations with Repetition CalculatorHow many ordered sequences of r positions you can build from n symbols when repeats are allowed.
• Poisson Distribution CalculatorThe chance of exactly k events in one interval when they arrive independently at an average rate λ.
• Probability Union CalculatorThe addition rule P(A∪B) = P(A) + P(B) − P(A∩B) — the chance that A happens, B happens, or both do.
• Sample Size CalculatorHow many people a survey needs: n = z² × p × (1 − p) ÷ E², for a confidence level and a margin of error.
• Standard Error CalculatorCalculate the standard error of a mean from SD and sample size, with examples and clear limits: precision does not remove sampling bias.
• T-Statistic CalculatorThe one-sample t-statistic from a sample mean, a hypothesised mean, the sample standard deviation and the sample size.
• Z-Score CalculatorTurn a raw value into a z-score from the mean and the standard deviation — how many standard deviations it sits from average.