Excel FORECAST function

The FORECAST function predicts a future value based on existing values by using the linear regression.

FORECAST function VS. FORECAST.LINEAR function

Starting from Excel 2016, the FORECAST function has been replaced by the FORECAST.LINEAR function. Although they can both be used to predict a future value based on given values, the FORECAST.LINEAR function is more recommended for future use, because the FORECAST function will eventually be deprecated in future versions of Excel.

Syntax

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

Arguments

• x (required): The data point (x value) for which you want to predict a y value;
• known_y’s (required): The dependent array or range of y values;
• known_x’s (required): The independent array or range of x values.

Remarks

y = a + bx

where

and

and and are the averages of know_x’s and known_y’s.

Return value

It returns a numeric value.

Example

As shown in the table below, there is a list of monthly sales from January to August, to predict the sales along the linear trend for the next few months, you can try the FORECAST function as follows.

1. Firstly, you need to create a helper column (the FORECASE column in this case).

Tips: Creating a helper column helps to distinguish the predicted values from the actual values in a chart using different colors, which makes the chart more intuitive.

2. Find the cell containing the last sales (C13 in this case) in the Sales column, select a cell (D13) next to it in the helper column, and then enter a number that is the same as the last sales.

3. Select the cell (D14), copy or enter the formula below and press the Enter key to get the result. Then select the result cell and drag its AutoFill Handle down to get other predicted values.

=FORECAST(B14,$C$6:$C$13,$B$6:$B$13)

Then you can create a forecast chart based on the table data as shown in the screenshot below.

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