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.

Note: Microsoft has released new forecasting function in Excel 2016. The FORECAST function was replaced with FORECAST.LINEAR which uses the same syntax and calculation logic. Although the FORECAST is still available for backward compatibility, Microsoft advises to use the new FORECAST.LINEAR function instead.

Supported versions

  • All versions

FORECAST Function Syntax

FORECAST(x, known_y's, known_x's)


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.

Excel FORECAST Function

Note that the cell D19 has the same value with the last historical data just to connect lines in the graph.

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  • If you are using Excel 2016 or a newer version, prefer the LINEAR function.
  • The equation for the FORECAST is
    FORECAST Function Equatıon

    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