used by people in more than 220 countries!

Below you will find descriptions and links to 14 free statistics calculators for computing values associated with the t-distribution.

If you like, you may also use the search page to help you find what you need.

This calculator will tell you the minimum required total sample size and per-group sample size for a one-tailed or two-tailed t-test study, given the probability level, the anticipated effect size, and the desired statistical power level.

This calculator will tell you the beta level for a one-tailed or two-tailed t-test study (i.e., the Type II error rate), given the observed probability level, the observed effect size, and the total sample size.

This calculator will compute the 99%, 95%, and 90% confidence intervals for the mean of a normal population, given the sample mean, the sample size, and the sample standard deviation.

This calculator will compute the cumulative distribution function (CDF) for the noncentral t-distribution (i.e., the area under the noncentral t-distribution from negative infinity to t), given a t-value, the degrees of freedom, and the value of the noncentrality parameter.

This calculator will compute the cumulative distribution function (CDF) for Student's t-distribution (i.e., the area under the t-distribution from negative infinity to t), given a t-value and the degrees of freedom.

This calculator will tell you the (two-tailed) effect size for a Student t-test (i.e., Cohen's d), given the mean and standard deviation for two independent samples of equal size.

This calculator will conduct a complete one-sample t-test, given the sample mean, the sample size, the hypothesized mean, and the sample standard deviation. The results generated by the calculator include the t-statistic, the degrees of freedom, the critical t-values for both one-tailed (directional) and two-tailed (non-directional) hypotheses, and the one-tailed and two-tailed probability values associated with the test.

This calculator will tell you the one-tailed and two-tailed probability values of a t-test, given the t-value and the degrees of freedom.

This calculator will tell you the observed power for a one-tailed or two-tailed t-test study, given the observed probability level, the observed effect size, and the total sample size.

This calculator will compute the probability density function (PDF) for the noncentral t-distribution, given a t-value, the degrees of freedom, and the value of the noncentrality parameter.

This calculator will compute the probability density function (PDF) for Student's t-distribution, given a t-value and the degrees of freedom.

This calculator will tell you the Student t-value for a given probability and degrees of freedom. Student t-values for both one-tailed (right-tail) and two-tailed probabilities will be returned.

This calculator will compute the t-statistic and degrees of freedom for a Student t-test, given the sample mean, the sample size, the hypothesized mean, and the sample standard deviation.

This calculator will tell you the t-value and degrees of freedom associated with a Pearson correlation coefficient, given the correlation value r, and the sample size.