FINV function
Returns the inverse of the (righttailed) F probability distribution. If p = FDIST(x,...), then FINV(p,...) = x.
The F distribution can be used in an Ftest that compares the degree of variability in two data sets. For example, you can analyze income distributions in the United States and Canada to determine whether the two countries have a similar degree of income diversity.
Important This function has been replaced with one or more new functions that may provide improved accuracy and whose names better reflect their usage. Although this function is still available for backward compatibility, you should consider using the new functions from now on, because this function may not be available in future versions of Excel.
For more information about the new functions, see F.INV function and F.INV.RT function.
Syntax
FINV(probability,deg_freedom1,deg_freedom2)
The FINV function syntax has the following arguments:

Probability Required. A probability associated with the F cumulative distribution.

Deg_freedom1 Required. The numerator degrees of freedom.

Deg_freedom2 Required. The denominator degrees of freedom.
Remarks

If any argument is nonnumeric, FINV returns the #VALUE! error value.

If probability < 0 or probability > 1, FINV returns the #NUM! error value.

If deg_freedom1 or deg_freedom2 is not an integer, it is truncated.

If deg_freedom1 < 1 or deg_freedom1 ≥ 10^10, FINV returns the #NUM! error value.

If deg_freedom2 < 1 or deg_freedom2 ≥ 10^10, FINV returns the #NUM! error value.
FINV can be used to return critical values from the F distribution. For example, the output of an ANOVA calculation often includes data for the F statistic, F probability, and F critical value at the 0.05 significance level. To return the critical value of F, use the significance level as the probability argument to FINV.
Given a value for probability, FINV seeks that value x such that FDIST(x, deg_freedom1, deg_freedom2) = probability. Thus, precision of FINV depends on precision of FDIST. FINV uses an iterative search technique. If the search has not converged after 100 iterations, the function returns the #N/A error value.
Example
Copy the example data in the following table, and paste it in cell A1 of a new Excel worksheet. For formulas to show results, select them, press F2, and then press Enter. If you need to, you can adjust the column widths to see all the data.