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IMLOG10 Function

Excel 2007+

Summary

The Excel IMLOG10 function computes the base-10 logarithm of a complex number entered in standard x+yi format. This engineering function returns results as complex numbers, enabling logarithmic calculations on numbers with both real and imaginary components.

Syntax

IMLOG10(inumber)

Parameters

Parameter	Type	Required	Description
inumber	`Complex`	Yes	A complex number (entered as text in "x+yi" or "x+yj" format) for logarithm calculation

Using the IMLOG10 Function

IMLOG10 is valuable in fields like electrical engineering, telecommunications, and physics where complex numbers represent signals, impedances, or waves. Use it to analyze frequency responses, calculate signal attenuation, or process phasor data in logarithmic scale.

Common IMLOG10 Examples

Basic Complex Logarithm

=IMLOG10("3+4i")

Returns the base-10 logarithm of 3+4i, approximately 0.69897+0.40272i

Engineering Application

=IMLOG10("4.5-2.3j")

Calculates log base 10 of complex impedance, useful for frequency response analysis

Using COMPLEX Helper

=IMLOG10(COMPLEX(5,3))

Converts real/imaginary parts to complex number first, then calculates base-10 log

Frequently Asked Questions

Enter complex numbers as text strings in "x+yi" or "x+yj" format (i or j for imaginary unit).

Yes, reference cells containing properly formatted complex number text or use COMPLEX(real_part,imag_part).

IMLOG10 uses base 10 (common log), while IMLN uses natural log (base e). Use LOG10 for real numbers.

Common Errors and Solutions

#NUM! or #VALUE!

Cause: Invalid complex number format

Solution: Use correct "x+yi" format or COMPLEX() function

#VALUE!

Cause: Missing inumber argument or non-complex input

Solution: Provide exactly one complex number argument

Notes

Available only in Excel 2007 and later versions
Use COMPLEX(real_num, i_num) to create complex numbers from separate cells
Result is always a complex number even for purely real inputs
The formula relates to natural log: IMLOG10(z) = IMLN(z)/LN(10)

Compatibility

Available in: Excel 2007, Excel 2010, Excel 2013, Excel 2016, Excel 2019, Excel 2021, Microsoft 365

Not available in: Excel 2003 and earlier

Content last reviewed: December 9, 2025
Update frequency: As needed
Excel versions tested: Excel 2007+