One-Sample t-Test Calculator

This calculator performs a one-sample t-test, which checks whether the mean of your sample differs significantly from a specific value you have in mind. It answers a common question: is my data consistent with a particular target, standard or claim? You might test whether the average weight of a product matches its labelled value, whether students' average score differs from a national benchmark, or whether a process mean has drifted from its target. The test compares the gap between your sample mean and the hypothesized value against the variability in your data, producing a t statistic. A large t, far from zero, suggests the true mean really does differ from the test value; a small t suggests any difference could be chance. This calculator does the work. You paste your sample data and enter the hypothesized mean to test against, and it returns the t statistic, the sample mean, the degrees of freedom, and the value you tested. The results update as you type. Use it for statistics study, for quality control, or to test whether a measured average matches a claimed or target figure. The t statistic is the difference between the sample mean and the hypothesized value, divided by the standard error of the mean, which is the sample standard deviation over the square root of the sample size. The degrees of freedom are one less than the sample size. To complete the test, compare the magnitude of t against the critical value from the t distribution at your chosen significance level and degrees of freedom, or find the p-value; if the magnitude exceeds the critical value, the difference is statistically significant. The test assumes the sample is drawn from a roughly normal distribution, which matters most for small samples.

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t = (sample mean - hypothesized mean) / (sample SD / sqrt n). Degrees of freedom = n - 1. Compare against a t table. Assumes a roughly normal sample.