Engineering

BESSELK Function in Excel

Returns the modified Bessel function Kn(x).

Syntax

  • =BESSELK(x, n)

Arguments

  • x (required): Value to evaluate
  • n (required): Order of the Bessel function

Examples

  • =BESSELK(1.5, 1) - Modified Bessel K1(1.5) - Result: 0.278

BESSELK 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 x <= 0 or n < 0

Use cases

  • Heat conduction
  • Engineering
  • Physics

Frequently asked questions

  • What is the BESSELK function in Excel? BESSELK returns the modified Bessel function Kn(x). The syntax is =BESSELK(x, n). Typical use cases include heat conduction, engineering, physics.
  • How do I use the BESSELK function? To use BESSELK, type =BESSELK( 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 BESSELK not working in my Excel? Common issues with BESSELK include #NUM! if x <= 0 or n < 0. Start by checking the syntax =BESSELK(x, n), then verify each referenced cell or range.

Editorial review

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