Statistics Calculators 2026 - Mean, Std Dev, T-Test, P-Value
What makes the statistics category useful
This category groups calculators that solve closely related real-world tasks, so you can move from a quick estimate to a more specific planning tool without restarting the process.
Compute mean, median, mode, range, and quartiles for any dataset in one paste
Calculate sample and population standard deviation, variance, and standard error
Run t-test, z-test, chi-square, and F-test with the test statistic and p-value shown
Build 90, 95, and 99 percent confidence intervals around a sample mean
Find correlation coefficient, p-value, and degrees of freedom for paired data
Coursework and exam prep
Verify hypothesis testing, descriptive stats, and confidence intervals against your textbook working.
Research and reports
Generate test statistics, p-values, and intervals you can paste straight into a paper or memo.
A/B testing decisions
Check whether a conversion rate change is statistically significant before rolling it out.
All Statistics Calculators
Average Calculator
Calculate the arithmetic mean of numbers.
Mean Median Mode Calculator
Find mean, median, and mode of a dataset.
Standard Deviation Calculator
Calculate variance and standard deviation.
Standard Error Calculator
SEM from standard deviation and sample size with confidence ranges.
Confidence Interval Calculator
Calculate confidence intervals with adjustable levels.
T-Test Calculator
Run a one-sample t-test and get the p-value instantly.
Z-Test Calculator
Run a one-sample z-test with known population standard deviation.
F-Test Calculator
Compare two sample variances with an F-test.
Chi-Square Calculator
Run a chi-square goodness-of-fit test instantly.
Correlation Coefficient Calculator
Calculate Pearson r from paired data points.
Correlation P-Value Calculator
Test if a correlation is statistically significant.
Degrees of Freedom Calculator
Calculate degrees of freedom for t-tests and chi-square tests.
Test Statistic Calculator
Compute t, z, or chi-square test statistics from data.
Statistical Significance Calculator
Check if your A/B test or survey result is statistically significant.
P Value Calculator
p-value from t statistic and df.
Two-Tailed P Value Calculator
Two-tailed p-value from t and df.
One-Tailed P Value Calculator
One-tailed p-value from t and df.
Test Statistic to P Value Calculator
From t statistic to p-values.
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Read articleCategory FAQ
How do I calculate standard deviation?
Take each value minus the mean, square the difference, average those squared differences (sample uses n minus 1), then take the square root. For the dataset 2, 4, 4, 4, 5, 5, 7, 9 the population standard deviation is 2.0 and the sample standard deviation is 2.14.
What is the difference between a t-test and a z-test?
Use a z-test when the population standard deviation is known and the sample size is over 30. Use a t-test when the population standard deviation is unknown or the sample size is small. The t-test uses the t-distribution with n minus 1 degrees of freedom.
How do I interpret a p-value?
A p-value below 0.05 is conventionally treated as statistically significant, meaning the result is unlikely to be due to chance. A p-value above 0.05 means you fail to reject the null hypothesis at the 95 percent confidence level.
How do I build a 95 percent confidence interval?
For a normal distribution: mean plus or minus 1.96 times standard error. With a sample mean of 50, standard deviation 10, and n = 100, the standard error is 1.0 and the 95 percent interval is roughly 48.04 to 51.96.
What does the correlation coefficient r tell me?
r ranges from -1 to +1. Values near +1 mean a strong positive linear relationship, near -1 a strong negative one, and near 0 no linear relationship. r = 0.8 indicates a strong positive correlation but does not prove causation.
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