An XLSX file is an Excel spreadsheet created by Microsoft Excel or another spreadsheet program, such as OpenOffice Calc or Apple Numbers. It stores data in worksheets, which contain cells arranged in a grid of rows and columns, and may also contain charts, mathematical functions, styles, and formatting. XLSX files are commonly used to store financial data and to create simple or complex mathematical models.

XLSX file open in Microsoft Excel 2019 XLSX files are created using the Open XML standard, which was introduced in Microsoft Office 2007. They are stored as a compressed Zip archive, which contains a collection of individual files. The archive includes the file [Content_Types].xml, which describes the spreadsheet, and an XML file for each worksheet within the spreadsheet. Each cell in an XLSX spreadsheet may be formatted individually. For example, cells may have a number, text, currency, or another format, as well as color, border style, custom font, and size. Cells may also reference other cells to compute a resulting value. NOTE: XLSX files can be opened in Excel 2007 or later. They are also backward compatible with earlier versions of Excel via Open XML component support.