Creating a calculated field

PivotTables let you analyze the data in your original data source. They also let you add calculated fields that can create calculations based on that data. In this movie, I will show you how to create a calculated field using the Calculated sample file, which you can find in the Chapter02 folder of your Exercise Files archive. This PivotTable has four fields. They are Department, Quarter, Revenue, and Sales, and currently Department, Quarter, and Revenue are displayed within the body of the PivotTable. In this case, the PivotTable is based on data in the same workbook, but for the moment, let's assume that I don't have access to the original data; say it's stored in an external source, or it's a file that I'm not allowed to change for some reason.

If I want to perform a separate calculation on the data, such as by combining values into fields produce another value, then I can do so by adding a calculated field. To do that, I go up to the Analyze contextual tab, and then in the Calculations group, click the Fields, Items, & Sets button, and from list that appears click Calculated Field. Doing so displays the Insert Calculated Field dialog box. Now I can type a name for the field. I'll call it average sale, and then I can click in the Formula box, and Backspace over the 0 to start creating my formula.

In this case, I want to divide my total revenue by the number of sales. To add those fields to my formula, I click the first field, in this case, Revenue and then click the Insert Field button. Then I'll type a forward slash for divide, and then I want to divide by Sales. Click Insert Field again. So, my formula will divide my total Revenue by the number of Sales. I'll click Add to add the calculated field, and you can see that average sale now appears in the field list, and I'll click OK.

When you click OK and create your calculated field, Excel automatically adds it to the body of the PivotTable. So, let me drag the Sum of Revenue field out of the Values area, so we can focus on just the calculated field that I just created. When I do, you can see that the data summary shows the average sales for each department in each of the four quarters that are covered. Most of the data is in the $30-$50 range, but you'll notice that there are some large values. For example, in the Play and Sport departments in the first quarter, the average sale is quite low, whereas for Work, the average sale is quite high.

It's that type of insight that you can get from creating calculated fields. One thing I should point out is that the calculated field that I just created only exists in Excel's memory. It doesn't exist in the original data source. If I click Sheet1, which contains the original data source, you can see that there is no average sale column. Go back to Sheet2. However, Excel does store the new field that I just created inside of the pivot cache, which is the internal representation of the PivotTable.

The ability to create calculated fields means that you can perform all sorts of terrific calculations, and gain insight into your business data.