statistics Calculators
Last updated: May 2026
Mean Calculator
Compute the arithmetic mean (average) of any comma-separated list of numbers — the most common measure of central tendency in statistics.
Standard Deviation Calculator
Compute the sample standard deviation directly from three summary statistics — sample size n, the sum of values Σx, and the sum of squared values Σx².
Correlation Coefficient Calculator
Compute the Pearson correlation coefficient (r) between two variables from paired summary statistics — n, Σxy, Σx, Σy — to measure how strongly they move together linearly.
Z-Score Calculator
Convert any raw value into a z-score — the number of standard deviations it sits above or below the mean of its distribution.
Sample Size Calculator
Calculate the minimum number of respondents needed to estimate a population proportion within a given margin of error at a chosen confidence level — the standard formula behind almost every survey, poll, and quality audit.
Confidence Interval Calculator
Compute the lower and upper bounds of a confidence interval for a population mean using a sample mean, the standard error of that mean, and a critical z-value (1.645 / 1.96 / 2.576 for 90% / 95% / 99% confidence).
Variance Calculator
Compute population or sample variance from the sum of squared deviations and the sample size.
Linear Regression Slope Calculator
Calculate the slope of a least-squares linear regression line from summary statistics of paired x and y data.
Chi-Square Test Calculator
Compute the chi-square test statistic contribution for one observed-vs-expected category pair using χ² = (observed − expected)² / expected.
Coefficient of Variation Calculator
Compute the coefficient of variation (CV), a dimensionless measure of relative variability defined as the standard deviation divided by the mean, expressed as a percentage.
One-Sample T-Test Calculator
Compute the one-sample t-statistic to test whether your sample mean differs significantly from a known or hypothesised population mean.
One-Way ANOVA Calculator
Compute the F-statistic for a one-way ANOVA from the treatment and error sums of squares and their degrees of freedom.
Standard Error Calculator
Compute the standard error of the mean (SEM) from the sample standard deviation and sample size, SEM = s/√n.
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.
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.
Confidence Interval Calculator
Compute the margin of error around a sample mean for a 90%, 95%, or 99% confidence interval using the z-distribution.
Hypothesis Test Calculator
Compute a z-score or t-statistic to determine whether your sample mean differs significantly from a hypothesized population mean.
Linear Regression Calculator
Find the linear relationship between two variables by computing the slope, correlation coefficient, and R² from paired data points.
Chi-Square Test Calculator
Compute the chi-square statistic to test whether observed frequencies differ significantly from expected ones, or whether two categorical variables are independent.
Standard Error Calculator
Calculate the standard error of the mean to measure how precisely your sample mean estimates the true population mean.
Statistical Power Calculator
Determine the statistical power of a hypothesis test given effect size, sample size, and alpha level.
Descriptive Statistics Calculator
Compute key summary statistics — mean, median, variance, and standard deviation — from any list of numbers.
Correlation Coefficient Calculator
Compute the Pearson correlation coefficient r and coefficient of determination R² from summary statistics of paired data.
ANOVA F-Test Calculator
Compute the F-statistic for a one-way ANOVA test by entering sums of squares and degrees of freedom.
Chi-Square Test Calculator
Compute the chi-square (χ²) statistic from observed and expected frequencies to test goodness of fit or independence.
Binomial Probability Calculator
Compute the exact probability of getting exactly k successes in n independent trials, each with probability p.
Standard Deviation Calculator
Instantly find the standard deviation and variance of any numeric data set, choosing between population or sample formulas.
Normal Distribution Calculator
Find the cumulative probability P(X ≤ x) for a normal distribution given any mean, standard deviation, and x value.
Normal Distribution Calculator
Convert any raw value to a z-score using a custom mean and standard deviation, then find corresponding normal distribution probabilities.
P-Value Calculator
Convert a z-score (or any standard-normal test statistic) into a p-value for a one- or two-tailed hypothesis test, then see it visualised as the shaded tail area on the standard normal curve.
Mean, Median, Mode Calculator
Find any of the three classic measures of central tendency — mean, median, or mode — from a comma-separated list of numbers.
Linear Regression Calculator
Fit a least-squares regression line y = a + b·x to paired x and y values and read off the slope, intercept, or coefficient of determination (r²).
Margin of Error Calculator
Find the margin of error for a survey proportion at a chosen confidence level.
Odds Ratio Calculator
Compute the odds ratio from a 2×2 contingency table to measure the association between an exposure and an outcome.
Cohen's d Effect Size Calculator
Calculate Cohen's d — the standardized difference between two group means in pooled standard deviation units.
Number Needed to Treat (NNT) Calculator
Calculate the number of patients who must be treated to prevent one additional bad outcome, from the control and treatment event rates.