What is the syntax for IMAGINARY in Excel?

The syntax for IMAGINARY is: =IMAGINARY(inumber)

What are common errors with IMAGINARY?

#NUM! if not valid complex number

What is IMAGINARY used for?

IMAGINARY extracts the imaginary coefficient from a complex number. For '3+4i', IMAGINARY returns 4 (not '4i', just the number). Used in electrical engineering, signal processing, and physics calculations involving complex numbers.

What is the difference between IMREAL and IMAGINARY?

For complex number a+bi: IMREAL returns 'a' (real part), IMAGINARY returns 'b' (imaginary coefficient). For '3+4i': IMREAL=3, IMAGINARY=4. Together they decompose any complex number into its components.

How do I calculate with complex numbers in Excel?

Use IM functions: IMSUM for addition, IMSUB for subtraction, IMPRODUCT for multiplication, IMDIV for division. Example: =IMPRODUCT('3+4i','1+2i') multiplies two complex numbers. Results are complex number strings.

Engineering

IMAGINARY Function in Excel

Returns the imaginary coefficient of a complex number.

Syntax

=IMAGINARY(inumber)

Arguments

inumber (required): Complex number

Examples

=IMAGINARY("3+4i") - Get imaginary part - Result: 4

IMAGINARY in technical sheets

Document units in adjacent cells — many engineering functions require exact unit strings.
Use [CONVERT](/functions/convert/) for unit changes before specialized formulas.
Validate inputs with [ISNUMBER](/functions/isnumber/) and range checks.

Common errors

#NUM! if not valid complex number

Use cases

Complex number analysis
Engineering
Signal processing

Frequently asked questions

What is IMAGINARY used for? IMAGINARY extracts the imaginary coefficient from a complex number. For '3+4i', IMAGINARY returns 4 (not '4i', just the number). Used in electrical engineering, signal processing, and physics calculations involving complex numbers.
What is the difference between IMREAL and IMAGINARY? For complex number a+bi: IMREAL returns 'a' (real part), IMAGINARY returns 'b' (imaginary coefficient). For '3+4i': IMREAL=3, IMAGINARY=4. Together they decompose any complex number into its components.
How do I calculate with complex numbers in Excel? Use IM functions: IMSUM for addition, IMSUB for subtraction, IMPRODUCT for multiplication, IMDIV for division. Example: =IMPRODUCT('3+4i','1+2i') multiplies two complex numbers. Results are complex number strings.

Editorial review

Reviewed by Excel.Directory Editorial Team. Updated May 2026.