FORECAST.ETS Function in Excel: Forecast With Seasonality

FORECAST.ETS Function in Excel: Forecast With Seasonality featured illustration

📎 This article includes 1 downloadable practice file ↓

⏱ 2 min readUpdated 5 October 2026

StatisticsLevel: ExpertAvailable in: Excel 2016+

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

FORECAST.ETS uses exponential smoothing and detects seasonal patterns — the engine behind Excel’s Forecast Sheet.

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Syntax

=FORECAST.ETS(target_date, values, timeline, [seasonality], [data_completion], [aggregation])
Argument What it means
seasonality 1 = detect automatically; or 12 for monthly data with a yearly cycle.

Examples

Example 1

=FORECAST.ETS(A38, B2:B37, A2:A37, 12)

Next month’s sales from three years of monthly history.

💡 The timeline must have even steps (every month, every day). Gaps trigger #NUM!.

FORECAST.ETS in practice

Where you will use it

  • Next month's sales with seasonality
  • Demand planning
  • Footfall forecasts

Worked example

24 months of history in H:I (sales rising, with an October-November festive peak each year).

Month no.FormulaResult
25=ROUND(FORECAST.ETS(A2,$I$1:$I$24,$H$1:$H$24),0)159
26=ROUND(FORECAST.ETS(A3,$I$1:$I$24,$H$1:$H$24),0)162
27=ROUND(FORECAST.ETS(A4,$I$1:$I$24,$H$1:$H$24),0)164

Results calculated in Excel.

Mistakes people make

MistakeWhat to do instead
Swapping values and timelineOrder is (target, values, timeline); swapped gives #NUM!
Too little historySeasonality needs at least 2 full cycles; dates must be evenly spaced

FORECAST.LINEAR · TREND

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

⚡ Interactive Practice Lab & Formula Tester:

Test formulas dynamically in our web formula laboratory or download the companion Excel workbook.

Continue learning

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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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