The Excel GEOMEAN function returns the geometric mean for a set of numeric values. Geometric mean can be used to calculate average rate of return with variable rates.
Syntax:=GEOMEAN (number1, [number2], …)
The GEOMEAN function syntax has the following arguments:
 Number1, number2, … Number1 is required, subsequent numbers are optional. 1 to 255 arguments for which you want to calculate the mean. You can also use a single array or a reference to an array instead of arguments separated by commas.
Example: Let’s look at some Excel GEOMEAN function examples and explore how to use the GEOMEAN function as a worksheet function in Microsoft Excel:
Syntax: =GEOMEAN(A2:G2)
Result: 5.47698697
Based on the Excel spreadsheet above, the following GEOMEAN examples would return:
Syntax: =GEOMEAN(A3:G3)
Result: 2.393483066
Syntax: =GEOMEAN(A4:F4)
Result: 5.440086846
Syntax: =GEOMEAN(A5:D5)
Result: 6.160140576
Syntax: =GEOMEAN(A6:E6)
Result: 7.200411487
Syntax: =GEOMEAN(A7:G7)
Result: 34.86198727
Cells containing Text values, logical values, or no value are ignored by Excel GEOMEAN Function.
Note:
 Arguments can either be numbers or names, arrays, or references that contain numbers.
 Logical values and text representations of numbers that you type directly into the list of arguments are counted.
 If an array or reference argument contains text, logical values, or empty cells, those values are ignored; however, cells with the value zero are included.
 Arguments that are error values or text that cannot be translated into numbers cause errors.
 If any data point ≤ 0, GEOMEAN returns the #NUM! error value.

The equation for the geometric mean is: