# The Excel LOG10 Function

Base 10 Logarithm

The Logarithm of a number, to a given base, is the power to which the base must be raised to give that number.

The Base 10 Logarithm of a number, (also known as the Common Logarithm and written as Log10(x) ), is the logarithm to the base 10.

Therefore,

If   10x = y   Then   Log10(y) = x
Related Function:
LOG Function

## Function Description

The Excel LOG10 function calculates the base 10 logarithm of a given number.

The syntax of the function is:

LOG10( number )

where the number argument is the positive real number that you want to calculate the base 10 logarithm of.

## Log10 Function Examples

The following spreadsheet provides four examples of the Excel Log10 function:

Formulas:
A
1=LOG10( 100 )
2=LOG10( 1000 )
3=LOG10( 0.001 )
4=LOG10( 25 )
Results:
AB
12  102 = 100; Therefore, Log10(100) = 2
23  103 = 1000; Therefore, Log10(1000) = 3
3-3  10-3 = 0.001; Therefore, Log10(0.001) = -3
41.397940009  101.397940009 = 25; Therefore, Log10(25) = 1.397940009

For further examples of the Excel Log10 function, see the Microsoft Office website.

## Log10 Function Errors

If you get an error from the Excel Log10 function, this is likely to be one of the following:

Common Errors
 #NUM! - Occurs if the supplied number argument is negative or zero. #VALUE! - Occurs if the supplied number argument is non-numeric.