XLSX file: what it is, its limits and how to open one

What is an XLSX file?

An XLSX file is a spreadsheet in the Office Open XML format, the default file type for Microsoft Excel since 2007. It stores sheets, formulas, formatting and charts.

XLSX vs XLS

XLS is Excel’s older binary format. XLSX replaced it with a ZIP archive of XML files that is smaller and easier for other software to read. It also raised the size limits: the XLSX row limit is 1,048,576 rows by 16,384 columns per sheet, against 65,536 rows by 256 columns in XLS.

XLSX vs CSV

An XLSX file can hold several sheets, formulas, formatting and charts. A CSV file holds one table of plain values separated by commas, with no formulas or formatting. Use XLSX for working files and CSV for moving data between systems.

How to open an XLSX file

Excel opens it natively, and most spreadsheet apps can import it. You can also open XLSX without Excel in a browser: Arkenso Docs opens .xlsx files as live spreadsheets your team can edit together, and exports them back to Excel at any time.

What survives the round trip

Values, most formulas and basic formatting move between spreadsheet apps reliably. Macros, unusual functions and advanced charts may not, so check those after moving a file from one program to another.

Last reviewed 2026-11-01.

Related terms

  • CSV file — A CSV file is a plain-text table in which each line is a row and the values in a row are separated by commas.
  • XLOOKUP — XLOOKUP is a spreadsheet function that searches one range for a value and returns the matching item from another range.
  • DOCX file — A DOCX file is a word-processing document in the Office Open XML format, the default file type for Microsoft Word since 2007.

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