Engineering

IMSUB Function in Excel

Returns the difference of two complex numbers.

Syntax

  • =IMSUB(inumber1, inumber2)

Arguments

  • inumber1 (required): Complex number to subtract from
  • inumber2 (required): Complex number to subtract

Examples

  • =IMSUB("5+3i", "2+1i") - Subtract complex numbers - Result: 3+2i

IMSUB 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 numbers

Use cases

  • Complex arithmetic
  • Engineering
  • Mathematics

Frequently asked questions

  • What is the IMSUB function in Excel? IMSUB returns the difference of two complex numbers. The syntax is =IMSUB(inumber1, inumber2). Typical use cases include complex arithmetic, engineering, mathematics.
  • How do I use the IMSUB function? To use IMSUB, type =IMSUB( in a cell and provide the required arguments. Excel will show you the syntax and parameter hints as you type. Make sure to close the parentheses and press Enter to execute the function.
  • Why is IMSUB not working in my Excel? Common issues with IMSUB include #NUM! if not valid complex numbers. Start by checking the syntax =IMSUB(inumber1, inumber2), then verify each referenced cell or range.

Editorial review

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