LOGEST Function in Excel: Exponential Curve Fit

LOGEST Function in Excel: Exponential Curve Fit featured illustration

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⏱ 2 min readUpdated 5 October 2026

StatisticsLevel: ExpertAvailable in: Excel 2007+

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

LOGEST fits y = b·mˣ and returns m (the growth factor) and b. m of 1.05 means 5% growth per period.

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Syntax

=LOGEST(known_ys, [known_xs], [const], [stats])
Argument What it means
known_ys Positive values.

Examples

Example 1

=INDEX(LOGEST(C2:C13, A2:A13), 1) - 1

Average monthly growth rate of sign-ups.

LOGEST in practice

Where you will use it

  • Fit exponential growth
  • Growth rate of users
  • Compound trend statistics

Worked example

OutputFormulaResult
Growth factor=ROUND(CHOOSE(ROW()-1,INDEX(LOGEST({100,110,121,133,146,161},{1,2,3,4,5,6}),1),INDEX(LOGEST({100,110,121,133,146,161},{1,2,3,4,5,6}),2),INDEX(LOGEST({100,110,121,133,146,161},{1,2,3,4,5,6}),1)-1),4)1.0997
Start value=ROUND(CHOOSE(ROW()-1,INDEX(LOGEST({100,110,121,133,146,161},{1,2,3,4,5,6}),1),INDEX(LOGEST({100,110,121,133,146,161},{1,2,3,4,5,6}),2),INDEX(LOGEST({100,110,121,133,146,161},{1,2,3,4,5,6}),1)-1),4)90.9481
Monthly growth %=ROUND(CHOOSE(ROW()-1,INDEX(LOGEST({100,110,121,133,146,161},{1,2,3,4,5,6}),1),INDEX(LOGEST({100,110,121,133,146,161},{1,2,3,4,5,6}),2),INDEX(LOGEST({100,110,121,133,146,161},{1,2,3,4,5,6}),1)-1),4)0.0997

Results calculated in Excel.

Mistakes people make

MistakeWhat to do instead
Reading outputFirst value is the growth factor (1.1 = 10%)
ZerosValues must be positive

GROWTH · LINEST

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📎 Practice files for this article

  • 📗
    Practice workbook: Statistics advanced33 tasks on realistic sales data — type your formula, the Check column turns green when it is right. Answers sheet included.
    ⬇ XLSX · 36 KB

Free to use for learning. Files with macros (.bas) are plain text — import them with Alt+F11 → File → Import File, and always test on a copy.

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