What is a .xlsx file? (XLSX)

XLSX is the modern Excel spreadsheet format. Like DOCX it is a zipped bundle of XML, holding your cells, formulas, charts and multiple sheets, and it opens in Excel, Google Sheets and LibreOffice alike.

What is a .xlsx file used for?

XLSX stores everything a spreadsheet needs: values, formulas, formatting, charts, pivot tables and many sheets, all as compressed XML.

It replaced the old binary XLS in 2007 and is now the universal spreadsheet format across office suites.

For raw data without formatting or formulas, the simpler CSV format is often exchanged instead.

How to open a .xlsx file

The .xlsx format opens in the following apps, grouped by operating system. If one app does not work, try another from the same list. For a step-by-step walkthrough, see how to open a .xlsx file.

Windows

Excel
LibreOffice Calc
Google Sheets

macOS

Excel
Numbers
LibreOffice Calc

Linux

LibreOffice Calc
OnlyOffice
Google Sheets

Web

Google Sheets
Office on the web

How to convert a .xlsx file

You can convert a .xlsx file to CSV, PDF, ODS using a conversion tool or the export menu of an app that opens it.

.xlsx file signature (magic bytes)

Programs recognise a .xlsx file by the bytes at the start of the file, not by its name. These are the signatures for XLSX. For a full breakdown, see the XLSX file signature page.

Hex signature	Offset	Note
50 4B 03 04	0	ZIP header (Office Open XML)

See the full magic-numbers reference for every format.

Frequently asked questions