The Excel HARMEAN function returns the harmonic mean for a set of numeric values. The harmonic mean is the reciprocal of the arithmetic mean of reciprocals. Harmonic mean can be used to calculate a mean that reduces the impact of outliers.
Syntax:= HARMEAN (number1, [number2], …)
The HARMEAN 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 HARMEAN function examples and explore how to use the HARMEAN function as a worksheet function in Microsoft Excel:
Syntax: =HARMEAN(A2:G2)
Result: 5.028375962
Cells containing Text values, logical values, or no value are ignored by Excel HARMEAN Function.
Based on the Excel spreadsheet above, the following HARMEAN examples would return:
Syntax: =HARMEAN(A3:G3)
Result: 1.58490566
Syntax: =HARMEAN(A4:F4)
Result: 4.576271186
Syntax: =HARMEAN(A5:D5)
Result: 5.829959514
Syntax: =HARMEAN(A6:E6)
Result: 6.653465347
Syntax: =HARMEAN(A7:G7)
Result: 29.22001823
Note:
 The harmonic mean is always less than the geometric mean, which is always less than the arithmetic mean.
 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, HARMEAN returns the #NUM! error value.

The equation for the harmonic mean is: