Probability Distribution Calculator

This calculator allows you to put in a significance level α to find a critical value or enter a test statistic to find a p-value.

• Select the statistical distribution (model) at the bottom right.
  • The T, Chi-Square, and F distributions require degrees of freedom.
  • Any degrees of freedom appear with the distribution name.
  • The input named for the model can be a test statistic or critical value.
• Use the section at the bottom left to enter any value.
• The other values will appear in the top section.
  • A test statistic or critical value goes in the first cell.
  • The left, right, both, and middle cells are all areas or probabilities.
• Results are rounded to six decimal places.

• Degrees of freedom (df) must be positive integers.
• Z and T can be positive or negative.
• Chi-Square and F cannot be negative.
• The areas (left, right, both, middle) must be greater than 0 and less than 1.
• JavaScript is required.