Enter t-value and degrees of freedom, then click a button.

Student's t-distribution is a continuous probability distribution used when estimating the mean of a normally distributed population with a small sample size and unknown standard deviation. It is the foundation of many statistical tests, including the t-test. The theoretical calculation involves the probability density function (PDF) and cumulative distribution function (CDF). The CDF gives the probability that a random variable following the t-distribution is less than or equal to a given t-value. The distribution is symmetric and bell-shaped, similar to the normal distribution but with heavier tails. As degrees of freedom increase, the t-distribution approaches the standard normal distribution. This calculator computes one-tailed and two-tailed p-values from a t-value, and also finds critical t-values for a given significance level (alpha=0.05). It is widely used in hypothesis testing, confidence intervals, and regression analysis.

1. Enter the t-value (test statistic) in the first field.
2. Enter the Degrees of Freedom (df) (sample size minus 1).
3. Click Calculate P-value (two-tailed) to get the one-tailed and two-tailed probabilities.
4. Click Calculate t-value from P to find critical t-value for alpha=0.05 and test significance.
5. The result shows p-values, critical t-values, and statistical significance interpretation.
6. Click Reset to restore default example values.