Reducing File Sizes for Workbooks with PivotTables

PivotTables are great for certain types of data analysis. Since PivotTables do quite a bit of number crunching, one of the techniques Excel uses to process them faster is to create an "intermediate dataset" to work with. This intermediate dataset, by default, is stored with the worksheet, so PivotTables can increase the size of your workbooks, sometimes dramatically.

If your workbook contains multiple PivotTables, all based on a single data source, Excel may create an intermediate dataset for each PivotTable, instead of using one intermediate dataset. This, of course, could increase the size of your workbook very rapidly.

You can control how Excel creates the intermediate dataset by modifying the options you choose in the PivotTable Wizard that puts your PivotTable together. If you have one PivotTable in your workbook, and when running the PivotTable Wizard a second time you specify the same data source that you used in the existing PivotTable, Excel informs you that "Your new report will use less memory if you base it on your existing report." If you click Yes, you will save memory because Excel will use the same intermediate data as it used for your other PivotTable.

You can also instruct Excel to not save your intermediate data tables in the same disk file with the workbook. This will make the size of your workbook file much, much smaller, but it will also require that PivotTables be refreshed every time you open your workbook. Follow these steps:

1. Run the PivotTable Wizard to create your PivotTable as you normally would.
2. When you get to the final screen of the PivotTable Wizard (the one with the checkered flag on it), click the Options button to display the PivotTable Options dialog box.
3. Clear the Save Data with Table Layout check box.
4. Choose the Refresh on Open check box.
5. Click on OK to close the PivotTable Options dialog box.
6. Finish the steps in the PivotTable Wizard.

You don't need to choose the Refresh on Open check box (step 4) if you don't want to, but if you don't, you will need to remember to manually refresh the PivotTable every time you open the workbook.

If you already have quite a few PivotTables in your workbook, and you don't want to go through the process of creating them again, you can use a macro to step through the PivotTables and modify the caching index and turn off the saving of the intermediate data to disk. The following macro will accomplish these tasks:

Sub PTReduceSize()
    Dim wks As Worksheet
    Dim PT As PivotTable

    For Each wks In ActiveWorkbook.Worksheets
        For Each PT In wks.PivotTables
            PT.RefreshTable
            PT.CacheIndex = 1
            PT.SaveData = False
        Next
    Next
End Sub

Once the macro runs (it won't take long), you should save your workbook using the Save As option. This will write a new workbook file, and you will be able to compare how much this change reduced the size of your workbook. Remember, however, that with the intermediate data not being saved to disk, the refreshing of the PivotTables takes longer when you first open the workbook.

ExcelTips is your source for cost-effective Microsoft Excel training. This tip (2851) applies to Microsoft Excel 97, 2000, 2002, and 2003. You can find a version of this tip for the ribbon interface of Excel (Excel 2007 and later) here: Reducing File Sizes for Workbooks with PivotTables.