XLS (Excel 97-2003 workbook)

XLS is the binary workbook format used by Microsoft Excel up to version 2003. It stores sheets, formulas, formatting, charts and macros in a single file. Each sheet is limited to 65,536 rows and 256 columns, a limit that the XML-based XLSX, the default since Excel 2007, raised considerably.

Use XLS only when an old version of Excel or a legacy system requires it. For new work, XLSX handles far larger sheets and is less prone to corruption, and CSV is the simpler choice when you only need to move raw data.

Source formats: .xls