Excel LOG Function

Excel LOG function

LOG as the name suggests the Excel function is used to calculate the logarithm of a given number, to the supplier base.


=LOG(number, [base])

Argument or Parameter

number (required)- The number for which you want to calculate the logarithm for.

base (optional)- This represents the base of the logarithm. If this parameter is not specified then it is by default taken as base 10.

How does the function work?

The Excel LOG function allows you to calculate the logarithm of a number with a specified base and returns numeric value which can be positive, negative (or) float.

Common Error associated

1 .# NUM!- Occurs if the given ‘number’ parameter or supplied base is negative or zero.

2..# DIV/0!- Occurs if the given ‘[base]. A parameter is equal to a ‘1’.

3.# VALUE!- Occurs if the given ‘number’ parameter or supplied [base] is non-numeric.


Number and base value can be directly entered for the formula (or) values can be entered in an excel worksheet as shown above and the result can be calculated using the cell numbers.


Let us take a different number and base parameter and check the result returned by a LOG function. The LOG function successfully calculates the logarithm of a number as shown in the figure.

Figure 1. The Excel LOG function used with different bases

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