Statistics

Calculate a confidence interval for a mean using the z-distribution. Free online confidence interval calculator for 90%, 95% and 99% levels showing margin of error, lower and upper bounds.

Calculate the Pearson correlation coefficient (r) between two data sets to measure the strength and direction of their linear relationship. Free online correlation calculator with r² and slope.

Compute mean, median, mode, range, variance and standard deviation for any data set.

Find the percentile value of any data set using linear interpolation. Free online percentile calculator that ranks your numbers and returns the value at any chosen percentile.

Calculate permutations (nPr) and combinations (nCr) for any n and r. Free online permutation and combination calculator using factorials, with instant results.

Calculate the probability of two independent events: P(A and B), P(A or B) and the complement P(not A). Free online probability calculator for single and combined events.

Calculate population and sample standard deviation, variance and mean of any data set instantly. Free online standard deviation calculator with step-by-step results.

Calculate a weighted average (weighted mean) from value and weight pairs. Free online weighted average calculator for grades, GPAs, prices and survey data.

Calculate the z-score (standard score) of a value from its mean and standard deviation. Free online z-score calculator showing how many standard deviations a point is from the mean.