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#Math

LOG

Excel Functions

Get the logarithm of a number

Syntax

EXCEL 
=LOG(number, [base])

Arguments

Parameter Description
number Number for which you want the logarithm.
base [optional] Base of the logarithm. Defaults to 10.

Return Value

The logarithm

Details

The LOG function returns the logarithm of a given number, using the provided base. The LOG function takes two arguments, number and base. The value provided for number should be a positive real number. The base argument represents the base of the logarithm. Base is optional and defaults to 10 if not provided. The logarithm of 16 with base 2 (the power to which 2 must be raised to equal 16) is 4: The logarithm of 100 with base 10 (the power to which 10 must be raised to equal 100) is 2: Because the base argument defaults to 10, the formulas below are equivalent:

Examples

Examples

The logarithm of 16 with base 2 (the power to which 2 must be raised to equal 16) is 4:

EXCEL 
=LOG(16, 2) // returns 4
Examples

The logarithm of 100 with base 10 (the power to which 10 must be raised to equal 100) is 2:

EXCEL 
=LOG(100,10) // returns 2
Examples

Because the base argument defaults to 10, the formulas below are equivalent:

EXCEL 
=LOG(100,10) // returns 2
=LOG(100) // returns 2
Examples

The LOG10 function also returns the base 10 logarithm of a number:

EXCEL 
=LOG10(100) // returns 2
=LOG10(1000) // returns 3

See Also

LOG10