Statistics Calculators
Last updated: October 2026
P-Value Calculator
Turn a z test statistic into a p-value for a two-tailed, left-tailed or right-tailed test, and see the tail area shaded on the normal curve.
Z-Score Calculator
Find how many standard deviations a value lies above or below the mean, and the matching percentile for normally distributed data.
Normal Distribution Probability Calculator
Calculate the probability that a normally distributed random variable falls within a specified range, below a threshold, or above one — using the mean and standard deviation that fully describe the bell curve.
Standard Error Calculator
Calculate the standard error of the mean to measure how precisely your sample mean estimates the true population mean.
Binomial Probability Calculator
Find the probability of exactly, at most, at least, fewer than or more than k successes in n independent trials with success probability p.
Margin of Error Calculator
Find the margin of error of a poll or survey percentage from the sample size, the result and the confidence level.
Sample Size Calculator
Work out how many survey responses you need for a chosen margin of error and confidence level, with an optional correction for small populations.
Standard Deviation Calculator
Paste a list of numbers to get the standard deviation.
Statistical Power Calculator
Determine the statistical power of a hypothesis test given effect size, sample size, and alpha level.
Mean, Median, Mode Calculator
Find the mean, median, mode or range of a list of numbers.
Linear Regression Calculator
Fit a least-squares linear regression and read off the slope of the best-fit line y = a + b·x, using summary statistics (n, Σx, Σy, Σxy, Σx²) of paired x and y data.
Confidence Interval Calculator
Get a confidence interval for a mean from the sample mean, standard deviation and sample size, using the t distribution or z.
Chi-Square Test Calculator
Compute the chi-square test statistic contribution for one observed-vs-expected category pair using χ² = (observed − expected)² / expected.