The FORECAST function is a Statistical function that predicts a future value by using existing values along with a linear trend (linear regression). You can use the forecasting function to predict future sales, inventory requirements, or consumer trends. In this guide, we’re going to show you how to use the FORECAST function and go over some tips and error handling methods.
- All versions
FORECAST Function Syntax
|x||The data point to use to predict a value.|
|known_y's||The dependent array or range of data (y values).|
|known_x's||The independent array or range of data (x values).|
FORECAST Function Examples
The FORECAST function predicts the value of data point x by given historical known_y's values and known_x's data points.
In our example, our historical data resides in the range B5:C19. See that the cell D20 has the FORECAST to predict the value based on B20.
A single forecasted value will not tell you much. The best way to review and compare the forecasted data is to forecast for more points and use a line chart to see the trend. All you need to do is to generate more data points and copy the formula. Just pay attention to absolute and relative references, since you will want to keep ranges of the historical data.
Note that the cell D19 has the same value with the last historical data just to connect lines in the graph.
- If you are using Excel 2016 or a newer version, prefer the LINEAR function.
- The equation for the FORECAST is
x = AVERAGE(known_x's)
y = AVERAGE(known_y's)
- If x is not a number, the function returns #VALUE!
- If known_y's or known_x's is empty or not at the same size, the function returns the #N/A
Excel Forecasting Functions
|Linear regression-based forecasting||FORECAST.LINEAR|
|Forecasting with Exponential Triple Smoothing||FORECAST.ETS|
|Seasonality in forecasting using Exponential Triple Smoothing||FORECAST.ETS.SEASONALITY|
|Confidence interval in a forecasting using Exponential Triple Smoothing||FORECAST.ETS.CONFINT|
|Statistical values in forecasting using Exponential Triple Smoothing||FORECAST.ETS.STAT|