Excel LOG10 function

Purpose

Get the base-10 logarithm of a number

Return value

The logarithm

Syntax

=LOG10(number)

number - The positive number for which you want the base-10 logarithm.

Using the LOG10 function

LOG10 returns the base-10 logarithm of a number. In simple terms, it answers the question: "10 raised to what power gives me this number?" The table below shows how LOG10 works and how it is related to raising 10 to a specific power:

Number	LOG10	Because
1000	3	10³ = 1000
100	2	10² = 100
10	1	10¹ = 10
1	0	10⁰ = 1
0.1	-1	10⁻¹ = 0.1
0.01	-2	10⁻² = 0.01

For numbers that aren't exact powers of 10, LOG10 will return get decimals:

Number	LOG10
50	1.699
3697	3.568
0.3697	-0.432

To use Excel's LOG10 function, just supply a number:

=LOG10(1000) // returns 3
=LOG10(100) // returns 2
=LOG10(10) // returns 1
=LOG10(1) // returns 0
=LOG10(0.1) // returns -1
=LOG10(0.01) // returns -2