FORECAST.ETS.CONFINT function

Gives the ± range around a FORECAST.ETS prediction, so you can show “expected 120 ± 15”.

Works in desktop Excel only

Syntax

=FORECAST.ETS.CONFINT(target_date, values, timeline, [confidence_level], [seasonality], [data_completion], [aggregation])

How to use FORECAST.ETS.CONFINT in Excel, step by step

FORECAST.ETS.CONFINT 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
An evenly spaced timeline

Set up the forecast first. Follow the FORECAST.ETS steps so B38 holds the forecast for the date in A38.
Calculate the interval. In C38 type =FORECAST.ETS.CONFINT(A38,$B$2:$B$37,$A$2:$A$37,0.95). 0.95 means a 95% confidence level.
Build the band. Lower bound =B38-C38, upper bound =B38+C38. Chart all three as lines.

Example

=FORECAST.ETS.CONFINT(A38,$B$2:$B$37,$A$2:$A$37,0.95)

Result: e.g. 14.8 (forecast ± 14.8)

A wider interval means the history is noisy or short.