Summary

The Excel IMAGINARY function returns the imaginary part of a complex number.

Purpose 

Get the imaginary part of a complex number

Return value 

The imaginary part of a complex number

Syntax

=IMAGINARY(inumber)
  • inumber - The string representing a complex number.

How to use 

The Excel IMAGINARY function returns the imaginary part of a complex number. For example:

=IMAGINARY("4+3i") // returns 3
Excel handles complex numbers as strings formatted like "x+yi" or "x+yj". Use the COMPLEX function to get the string representing a complex number.

Explanation

A complex number is drawn as an arrow in the complex plane, where the horizontal axis corresponds to the real part of the number and the vertical axis corresponds to the imaginary part of the number. For example, the complex number "2-5i" is drawn below.

A complex number is drawn as an arrow in the complex plane.

The IMAGINARY function returns the vertical component of the complex number.

=IMAGINARY("2-5i") // returns -5

Notes:

  • IMAGINARY returns a #NUM error when the input does not represent a valid complex number.

Images courtesy of wumbo.net.

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Dave Bruns

Hi - I'm Dave Bruns, and I run Exceljet with my wife, Lisa. Our goal is to help you work faster in Excel. We create short videos, and clear examples of formulas, functions, pivot tables, conditional formatting, and charts.