Excel like a finance pro.
Statistical function
FORECAST.ETS
Predicts a future value using exponential smoothing with seasonality.
When to use it
Forecasts a future value using exponential triple smoothing, which picks up trend and seasonality automatically. Needs a timeline with a constant step.
The shape of it
- Syntax
=FORECAST.ETS(target_date, values, timeline, [seasonality], ...)
Worked examples
Seasonal forecast
=FORECAST.ETS(DATE(2026,1,1),B2:B37,A2:A37) → 1,284
Next January from 36 months of demand with a yearly pattern.
Fixed seasonality
=FORECAST.ETS(A38,B2:B37,A2:A37,12) → 1,284
Seasonality forced to 12 periods instead of auto-detected.
No seasonality
=FORECAST.ETS(A38,B2:B37,A2:A37,1) → 1,205
Seasonality 1 turns the seasonal component off.
Worth knowing
- The Data tab, Forecast Sheet button, builds the timeline, forecast, and confidence band for you with these functions.
- Timeline steps must be equal (every day, every month); missing points are interpolated up to 30%.
- FORECAST.ETS.CONFINT gives the confidence interval to show as a band.
Where it goes wrong
- #VALUE! when the timeline is irregular or has duplicates.
- Needs at least two full seasons to detect seasonality reliably.
Related
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