Statistics Calculators
Descriptive stats, spread and probability. 10 free tools and counting.
Summarise data and reason about uncertainty: averages and spread, percentiles and z-scores, then the inferential tools — confidence intervals and the sample size a survey actually needs. Each tool states its assumptions, because in statistics the assumptions are half the answer.
Mean, Median & Mode
Central tendency of a data set in one place.
Standard Deviation
Variance and standard deviation, sample or population.
Z-Score Calculator
Standardise a value against a distribution.
Probability
Single and combined event probabilities.
Permutations & Combinations
nPr and nCr for counting problems.
Confidence Interval
Confidence interval and margin of error for a sample mean.
Sample Size Calculator
How many survey responses you need for a target margin of error.
Percentile Calculator
Find any percentile and the quartiles of a list of numbers.
Correlation & Linear Regression
Pearson correlation, best-fit line and R² from two paired data sets.
Binomial Probability
Chance of exactly, at most or at least k successes in n independent trials.