How to Tell Which Version of Excel Created a Spreadsheet

1. Locate the Excel file on your computer. For example, run Windows Explorer to find the file.
2. Look at the file extension for the file. The file extension is the set of characters that come after the dot. For example, you might see .xls.
3. Decide which version of Excel created the spreadsheet. If the file extension is .xlsx, Excel 2007 created the file. If the file extension is .xls, Excel 2003 (or an earlier version of the software) most likely created the file. There is an exception: Excel 2007 has the capability of being able to make backwards compatible (.xls) files.