FORECAST.ETS function
Forecasts a future value with exponential smoothing that understands seasons (for example monthly sales that peak every December).
Syntax
=FORECAST.ETS(target_date, values, timeline, [seasonality], [data_completion], [aggregation])How to use FORECAST.ETS in Excel, step by step
FORECAST.ETS doesn’t run in a web practice sheet because it uses Excel’s own exponential smoothing engine (AAA version of ETS). Follow these steps in Excel itself.
You’ll need
- Excel 2016 or later for Windows/Mac, or Excel for the web
- A timeline with evenly spaced dates (every day, every month …)
- Lay out the history. Dates in A2:A37 (one per month, no gaps) and sales in B2:B37.
- Add the date to forecast. In A38 type the next month, e.g. 2025-01-01.
- Write the formula. In B38 type =FORECAST.ETS(A38,$B$2:$B$37,$A$2:$A$37). Excel detects the season length automatically.
- Set the season yourself (optional). Use 12 for monthly data with yearly seasons: =FORECAST.ETS(A38,$B$2:$B$37,$A$2:$A$37,12).
- Or use the Forecast Sheet. Select both columns › Data › Forecast Sheet. Excel builds the formulas, a chart and confidence bands for you.
Example
=FORECAST.ETS(A38,$B$2:$B$37,$A$2:$A$37,12)Result: The predicted sales for January
Up to 30% missing points are filled in automatically (data_completion 1).
For a simple straight-line forecast use FORECAST.LINEAR — it works in the practice sheet.