Note: Starting with Excel 2016, the FORECAST function was replaced with the FORECAST.LINEAR function. Microsoft recommends replacing FORECAST with FORECAST.LINEAR, since FORECAST will eventually be deprecated. Note: Starting with Excel 2016, the FORECAST function was replaced with the FORECAST.LINEAR function. Microsoft recommends replacing FORECAST with FORECAST.LINEAR, since FORECAST will eventually be deprecated. In statistics, linear regression is an approach for modeling the relationship between a dependent variable (y values) and an independent variable (x values). FORECAST.LINEAR uses this approach to calculate a y value for a given x value based on existing x and y values. In other words, for a given value x, FORECAST.LINEAR returns a predicted value based on the linear regression relationship between x values and y values.

### Example

In the example shown above, the formula in cell D13 is: where sales (C5:C12) and periods (B5:B12) are named ranges. With these inputs, the FORECAST.LINEAR function returns 1505.36 in cell D13. As the formula is copied down the table, FORECAST.LINEAR returns predicted values in D13:D16, using values in column B for x. The chart to the right shows this data plotted in a scatter plot. Note: Although FORECAST calculates future value predictions, it can also be used to interpolate and even predict the past. Mark at Excel Off The Grid has a detailed explanation here.

### Notes

If x is not numeric, FORECAST.LINEAR returns a #VALUE! error. If known_ys and known_xs are not the same size, FORECAST.LINEAR will #N/A. If the variance of known_x values is zero, FORECAST.LINEAR will return #DIV/0!.

### Dave Bruns

Hi - I’m Dave Bruns, and I run Exceljet with my wife, Lisa. Our goal is to help you work faster in Excel. We create short videos, and clear examples of formulas, functions, pivot tables, conditional formatting, and charts.