Statistics Calculators
Explore free statistics calculators for data summaries, probability, confidence intervals, sample size, correlation, regression, and hypothesis testing. Each tool explains its formula, assumptions, and result.
Mode Calculator
Find the mode or modes of a numeric data set, frequency counts, sample size, and whether the data are unimodal or multimodal.
Variance Calculator
Calculate sample or population variance with the mean, standard deviation, sample size, and correct n or n−1 denominator.
Z-Score Calculator
Calculate a z-score from a raw score, mean, and standard deviation, with direction and an estimated standard-normal percentile.
Percentile Calculator
Calculate any percentile from a numeric data set using inclusive linear interpolation, with rank, minimum, maximum, and sample size.
Probability Calculator
Calculate basic event probability from favorable and total equally likely outcomes, including percent, decimal, complement, fraction, and odds.
Confidence Interval Calculator
Calculate a two-sided 90%, 95%, or 99% confidence interval for a population mean using sample mean, sample SD, size, and Student’s t.
Sample Size Calculator
Estimate survey sample size for one proportion from confidence, margin of error, expected proportion, and optional finite population size.
Correlation Calculator
Calculate Pearson correlation from paired x and y data, with r, R-squared, relationship direction, strength, means, and sample size.
Linear Regression Calculator
Fit a least-squares linear regression from paired x and y data and calculate slope, intercept, equation, Pearson r, R-squared, and sample size.
Interquartile Range Calculator
Calculate Q1, median, Q3, interquartile range, and 1.5×IQR outlier fences from numeric data using stated linear interpolation.
Coefficient of Variation Calculator
Calculate sample or population coefficient of variation with mean, standard deviation, variance, and sample size for ratio-scale data.
Chi-Square Calculator
Calculate a chi-square goodness-of-fit statistic, degrees of freedom, p-value, and significance conclusion from observed and expected counts.
About Our Statistics Calculators
These tools support common U.S. classroom, workplace, survey, research, and data-analysis questions. Start with a descriptive summary such as the mode calculator or variance calculator, then use a method suited to the question you are asking.
Choose a tool that matches the question
Use the confidence interval calculator to quantify uncertainty around a mean, the sample size calculator to plan a simple proportion survey, or the correlation calculator before fitting the related regression model.
Transparent methods and assumptions
Every page names its formula and practical limits. NIST’s e-Handbook of Statistical Methods is a primary methodology reference, while the sample-size page also cites current CDC Epi Info guidance.
- Enter raw numeric values without currency signs or unit labels.
- Choose sample or population treatment when the distinction changes the denominator.
- Do not treat correlation as proof of causation.
- Check sampling, independence, distribution, and expected-count assumptions before acting on inferential results.
Statistics Calculator FAQs
Are the Statistics calculators free to use?
Yes. Every calculator in this category is free to use in a browser without creating an account.
Do the calculators upload my data?
No. The calculations run in your browser, and the numeric values you enter are not sent to a calculation server.
Should I choose sample or population formulas?
Choose sample when the entered values are observations used to estimate a larger population. Choose population when the list is the complete population you intend to describe.
Why can statistical software give a slightly different percentile?
Software packages may use different valid percentile and quartile conventions. Each calculator on this site states the method it uses.
Can I copy, download, or print a result?
Yes. Every new Statistics calculator includes Copy, Download, and Print actions once a valid result has been calculated.
Are these tools suitable for professional research?
They are useful for transparent calculations and checks, but professional research also requires study design, data cleaning, assumption checks, and qualified interpretation.
Do the calculators work on mobile devices?
Yes. The category, inputs, and BMI-style result panels are responsive for phones, tablets, laptops, and desktops.
Where can I verify the statistical methods?
Each calculator page includes its formula, assumptions, limitations, and links to authoritative sources such as the NIST/SEMATECH e-Handbook or CDC guidance where relevant.