P-value Calculator
Turn any test statistic into its exact p-value in one step: pick the distribution (z, t, chi-square or F), type the statistic and its degrees of freedom, and choose the tail. The calculator uses the same distribution functions as R (pnorm, pt, pchisq, pf), verified to at least six significant digits — so the number matches what SPSS, R or your textbook tables would give. Use it to finish a hand calculation, check a homework answer, or recover the exact p-value a paper reported only as "p < .05". Chi-square and F tests are right-tailed by convention; for z and t you can switch between two-tailed and one-tailed (left/right). Everything runs in your browser — nothing is uploaded.
AI Report
Let AI interpret your results: a downloadable Word document in APA 7 / business report format.
Frequently asked questions
How do I report a p-value in APA 7 format?
Report the exact p-value to two or three decimals with no leading zero, e.g. "p = .031"; only use an inequality for very small values: "p < .001". The p-value always accompanies the test statistic and degrees of freedom, e.g. "t(24) = 2.31, p = .030". The AI Report button turns your result into a complete APA 7 results sentence.
Should I use a one-tailed or two-tailed p-value?
Two-tailed is the standard default: it tests for a difference in either direction and is what SPSS and R report. Use one-tailed only when the direction was fixed before collecting data and the opposite direction is meaningless for your hypothesis — and say so explicitly when reporting.
Why is there no tail choice for chi-square and F?
Chi-square and F statistics are squared-deviation measures: departures from the null hypothesis in any direction push the statistic to the right. The conventional test therefore only looks at the right tail — that is what pchisq(..., lower.tail=FALSE) and pf(..., lower.tail=FALSE) compute in R.