The Excel PROB Function

Function Description

Given a list of values and a corresponding list of probabilities, the Excel PROB function calculates the probability associated with a given range.

The syntax of the function is:

PROB( x_range, prob_range, [lower_limit], [upper_limit] )

where the function arguments are as follows:

x_range - An array of values that have associated probabilities.
prob_range -

The array of probabilities corresponding to the values in x_range.

(This array must have the same length as the x_range array and the values in prob_range must add up to 1).
lower_limit - The lower bound of the range of values for which you want to calculate the probability.
[upper_limit] -

An optional value that denotes the upper bound of the range that you want to calculate the probability for.

(If the [upper_limit] is omitted, the function simply returns the probability associated with the value of the supplied lower_limit).

Prob Function Examples

Columns A and B of the spreadsheet below contain a set of values and their associated probabilities. These values and probabilities are provided to the Excel Prob functions in cells C1-C3 of the spreadsheet.

  A B C D
1 x probability =PROB( A2:A9, B2:B9, 3 ) - Returns the value 0.22
2 0 0.1 =PROB( A2:A9, B2:B9, 3, 5 ) - Returns the value 0.52
3 1 0.15 =PROB( A2:A9, B2:B9, 8, 10 ) - Returns the value 0
4 2 0.17    
5 3 0.22    
6 4 0.21    
7 5 0.09    
8 6 0.05    
9 7 0.01    

For further details and examples of the Excel Prob function, see the Microsoft Office website.

Prob Function Errors

If you get an error returned from the Excel Prob Function, this is likely to be one of the following:

Common Errors
#NUM! -

Occurs if either:

  • Any value in the supplied prob_range is <0 or >1
  • The values in the supplied prob_range do not add up to 1.
#N/A! - Occurs if the supplied x_range and prob_range arrays are of different lengths (i.e. contain different numbers of data points).