BESSELI Function in Excel: Modified Bessel Function In(x)

BESSELI Function in Excel: Modified Bessel Function In(x) 1
⏱ 1 min readUpdated 5 October 2026

EngineeringLevel: ExpertAvailable in: Excel 2007+

In this article
  1. Syntax
  2. Examples
  3. Example 1
  4. BESSELI in practice
  5. Where you will use it
  6. Worked example
  7. Mistakes people make
  8. Related functions

BESSELI returns the modified Bessel function In(x), used in heat transfer, signal processing and vibration problems.

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Syntax

=BESSELI(x, n)
Argument What it means
x Value
n Order (whole number, 0 or more)

Examples

Example 1

=ROUND(BESSELI(A2,B2),5)

Result: 0.98167. See the worked example table below for more cases.

BESSELI in practice

Where you will use it

  • Heat conduction in cylinders
  • Filter design
  • Engineering coursework

Worked example

xnFormulaResult
1.51=ROUND(BESSELI(A2,B2),5)0.98167
20=ROUND(BESSELI(A3,B3),5)2.27959
32=ROUND(BESSELI(A4,B4),5)2.24521

Results calculated in Excel.

Mistakes people make

MistakeWhat to do instead
Negative n#NUM!
n with decimalsTruncated to a whole number

BESSELJ · BESSELK

📚 Part of the free Excel course: Beginner → Expert · Try it in the Formula Lab or ask the AI Helper.

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