Lookup inputs
Result
Educational lookup only. Verify regulated reports, publications, or graded statistical work with the required software or table convention.
How to use this lookup
- Choose the distribution that matches your test statistic: z, t, chi-square, or F.
- Choose p-value mode when you know the statistic, or critical value mode when you know alpha.
- Match the tail to your alternative hypothesis or table convention before reading the verdict.
Rounding and accuracy notes
The calculator uses JavaScript float64 arithmetic with regularized beta and gamma functions from CalcBE's distribution runtime. Printed distribution tables usually round to three or four decimals, so the last digit can differ. Use the displayed values as a transparent educational lookup, and verify regulated reports or publications with your required statistical software.
Related statistics tools
To compute a statistic from data, use the t-test calculator, chi-square test calculator, or ANOVA calculator. To review a broader confidence interval workflow, use the CI & hypothesis test wizard. For A/B test conversion results, use the A/B test significance calculator.
FAQ
How do I choose left, right, or two-sided?
Use the right tail for statistics where unusually large values count against the null, the left tail when unusually small values matter, and two-sided for symmetric z or t tests where either direction is evidence.
Why are two-sided chi-square and F lookups treated as right-tail?
Most chi-square and F hypothesis tests use large positive statistics as evidence against the null. Two-sided definitions exist in special settings, but they are not a single universal table lookup, so this page labels the result as right-tail.
Why can my result differ from a printed distribution table?
Printed tables round probabilities and critical values to a few decimals. This page computes with JavaScript float64 arithmetic and rounds only for display, so the last shown digit can differ from a textbook table.
Which degrees of freedom should I enter?
For t and chi-square distributions, enter the single degrees-of-freedom value from your test. For F distributions, enter numerator df1 and denominator df2 in that order.
Is this a full hypothesis test calculator?
No. This page looks up p-values and critical values after you already know the test statistic and degrees of freedom. Use a t-test, chi-square, ANOVA, or CI workflow page when you need to compute the statistic from data.