Statistics Calculators

Turn a raw value into a z-score — how many standard deviations it sits above or below the mean — with its percentile under a normal curve.

Build a confidence interval for a mean from your sample mean, standard deviation and size — with the margin of error and the interval bounds.

Find the standard error of the mean from a sample standard deviation and size — how much the sample mean is expected to vary.

Work out how many people to survey for a target margin of error and confidence level, with an optional finite-population correction.

Find the margin of error for a survey or poll from its sample size, expected proportion and confidence level.

Compute the Pearson correlation coefficient r between two lists of numbers, with r-squared and a plain-language reading of the relationship.

Find the percentile rank of a value in a data set, or the value that sits at a given percentile.

Compute the coefficient of variation (CV) — standard deviation as a percentage of the mean — to compare relative spread across data sets.

Convert a z-score into a p-value from the normal distribution for a left, right or two-tailed test, with a significance verdict at 0.05.

Get the five-number summary — minimum, Q1, median, Q3 and maximum — plus the interquartile range and outlier fences for any data set.

Calculate relative risk (the risk ratio) from a 2×2 table of exposed and unexposed groups, with the underlying risks and a plain reading.

Paste a list of numbers to get the mean absolute deviation (MAD), plus the mean, variance and standard deviation.