Returns the inverse of the normal cumulative distribution for the specified mean and standard deviation.
Syntax
NORMINV(probability,mean,standard_dev)
Probability is a probability corresponding to the normal distribution.
Mean is the arithmetic mean of the distribution.
Standard_dev is the standard deviation of the distribution.
Remarks
 If any argument is nonnumeric, NORMINV returns the #VALUE! error value.
 If probability < 0 or if probability > 1, NORMINV returns the #NUM! error value.
 If standard_dev ≤ 0, NORMINV returns the #NUM! error value.
 If mean = 0 and standard_dev = 1, NORMINV uses the standard normal distribution (see NORMSINV).
Given a value for probability, NORMINV seeks that value x such that NORMDIST(x, mean, standard_dev, TRUE) = probability. Thus, precision of NORMINV depends on precision of NORMDIST. NORMINV uses an iterative search technique. If the search has not converged after 100 iterations, the function returns the #N/A error value.
Example
The example may be easier to understand if you copy it to a blank worksheet.
How to copy an example
 Create a blank workbook or worksheet.
 Select the example in the Help topic.
Note Do not select the row or column headers.
Selecting an example from Help
 Press CTRL+C.
 In the worksheet, select cell A1, and press CTRL+V.
 To switch between viewing the results and viewing the formulas that return the results, press CTRL+` (grave accent), or on the Formulas tab, in the Formula Auditing group, click the Show Formulas button.

A 
B 
Data 
Description 
0.908789 
Probability corresponding to the normal distribution 
40 
Arithmetic mean of the distribution 
1.5 
Standard deviation of the distribution 
Formula 
Description (Result) 
=NORMINV(A2,A3,A4) 
Inverse of the normal cumulative distribution for the terms above (42) 
