T-Test Calculator

Use a T-test when you want to compare the means of two groups or compare a sample mean to a population mean when the population standard deviation is unknown.

For a one-sample t-test, the formula is $t = (\bar{x} - \mu) / (s / \sqrt{n})$, where $\bar{x}$ is sample mean, $\mu$ is population mean, $s$ is sample SD, and $n$ is sample size.

In a one-sample t-test, degrees of freedom ($df$) are calculated as $n - 1$. This value is used to find the critical t-value in a statistical table.