When working with two Excel workbooks, instead of flipping back and forth to compare data, use Excel’s built-in “Compare” option to put those workbooks side by side. Here’s what you do:

  1. Open both workbooks you want to compare side by side.
  2. Select Window 〉 Compare Side by Side.
  3. There are two options for viewing the data of the two workbooks you are now comparing.
    • Click “Synchronous Scrolling” to scroll through both documents at the same time. Uncheck for independent scrolling.
    • You can also reset the scrolling position to the starting position by clicking the button “Reset Window Position”.
  4. When you are finished with your comparison, click Close Side by Side to return to the normal worksheet view.

Beginning with Excel 2013 for Windows, one is able to open multiple worksheets in different windows … puts an end to the flipping back and forth.