The Excel CHISQ.INV function returns the inverse of the left-tailed chi-square distribution — the value below which a given cumulative probability falls, for a stated number of degrees of freedom.
Syntax
| Argument | Description | |
|---|---|---|
probability | Required | A probability between 0 and 1 (the cumulative, left-tail area). |
deg_freedom | Required | The number of degrees of freedom (a positive integer; decimals are truncated). |
How to use it
CHISQ.INV answers the question “what chi-square value has this much area to its left?” It is the inverse of CHISQ.DIST(x, df, TRUE).
For critical values in a standard hypothesis test you usually want the right tail instead — that is what CHISQ.INV.RT gives. The two are mirror images: CHISQ.INV(0.95, df) equals CHISQ.INV.RT(0.05, df).
Left vs. right: CHISQ.INV takes the cumulative (left-tail) probability, while CHISQ.INV.RT takes the upper-tail probability (the significance level). Pick the one that matches how your textbook states the problem.
Try it: interactive demo
Pick a CHISQ.INV example to see the formula and its result.
Practice workbook
Frequently asked questions
What is the difference between CHISQ.INV and CHISQ.INV.RT?
CHISQ.INV uses the cumulative (left-tail) probability, while CHISQ.INV.RT uses the right-tail (upper) probability. They are complements: CHISQ.INV(0.95, df) = CHISQ.INV.RT(0.05, df).How is CHISQ.INV related to CHISQ.DIST?
CHISQ.DIST(x, df, TRUE) = p, then CHISQ.INV(p, df) = x.Does CHISQ.INV replace the old CHIINV function?
CHISQ.INV.RT, not CHISQ.INV. CHISQ.INV (left tail) has no pre-2010 twin.What probability values are valid?
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