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FORECAST.ETS Function
Summary
FORECAST.ETS leverages advanced Exponential Triple Smoothing (ETS) algorithms to deliver accurate time series predictions. This powerful function automatically detects seasonality patterns and provides reliable forecasts for business planning, sales projections, and trend analysis.
Syntax
FORECAST.ETS(target_date, values, timeline, [seasonality], [data_completion], [aggregation])Parameters
| Parameter | Type | Required | Description |
|---|---|---|---|
| target_date | Date |
Yes | The specific date or timeline position to forecast |
| values | Number array |
Yes | Numeric values representing historical observations |
| timeline | Date array |
Yes | Dates matching each value in the values array |
| seasonality | Number |
No | Season period length (auto=1, none=0) |
| data_completion | Number |
No | Missing data treatment method |
| aggregation | Number |
No | Method for aggregating groups of values |
Using the FORECAST.ETS Function
FORECAST.ETS transforms raw time series data into actionable predictions using sophisticated ETS algorithms. Ideal for forecasting sales, inventory needs, website traffic, or any sequential numeric data with temporal patterns.
Common FORECAST.ETS Examples
Basic Monthly Sales Forecast
=FORECAST.ETS(DATE(2024,1,1), B2:B13, A2:A13)Predicts January 2024 sales based on 12 months of historical data with auto seasonality.
Quarterly Revenue with Missing Data
=FORECAST.ETS(DATE(2024,4,1), C2:C13, B2:B13, 1, 2)Forecasts Q2 2024 using quarterly data, interpolating missing values.
Weekly Traffic Prediction
=FORECAST.ETS(A20, B2:B19, A2:A19, 7)Predicts week 20 traffic with explicit 7-day weekly seasonality.
Frequently Asked Questions
Common Errors and Solutions
#VALUE! error
Cause: Values or timeline arrays have different sizes
Solution: Ensure values and timeline arrays contain same number of elements
#NUM! error
Cause: Invalid seasonality or data_completion values
Solution: Use valid codes: seasonality (0,1,2+); data_completion (0,1,2)
Poor forecast accuracy
Cause: Insufficient historical data (<2 seasons)
Solution: Provide at least 2 full seasonal cycles
Notes
- Minimum 2 historical points required
- Optimal with 2+ seasonal cycles
- Returns #N/A if cannot compute reliable forecast
- Uses Microsoft AAA ETS algorithm
Compatibility
Available in: Excel 2016, Excel 2019, Excel 2021, Excel for Microsoft 365
Not available in: Excel 2013, Excel 2010, Excel 2007, Excel 2003
Content last reviewed: December 9, 2025
Update frequency: As needed
Excel versions tested: Excel 2016+, Excel for Microsoft 365