Forecast the future with Excel trendlines

Trying to predict the future based on past experiences, but you're lacking the right formula? If you've forgotten high school algebra, fear not. With trendlines, Excel can project future figures based on previous history. Mary Ann Richardson points the way.

Let's say you are keeping track of monthly sales figures for the past six months (January through June), and you want to know what the overall sales will likely be for the second half of the year. You can use trendlines to have Excel predict the answers based on your previous data. Follow these steps:

  1. Create a bar chart of the data you've tracked so far.
  2. Click on your chart, and then click on the data series.
  3. Go to Chart | Add Trendline.
  4. Click on the Options tab.
  5. In the Forecast section, click on the up arrow in the Forecast box until the entry in the box changes to 6.
  6. Click OK.

Excel will extend the trendline to show estimated monthly sales figures for the rest of the year.

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