XLSX — Microsoft Excel Workbook
XLSX is the default format of Microsoft Excel since 2007. Like DOCX, it's a ZIP container of XML files, and it's an open standard. An XLSX workbook holds one or more worksheets of cells, and each cell can contain values, formulas, formatting, validation rules and more.
Beyond the grid, workbooks can hold charts, pivot tables, images and named ranges — a complete data-analysis document.
What Excel (XLSX) files are used for
- Financial models, budgets and reports
- Data analysis and dashboards
- Anything humans read, sort, filter and annotate as a table
Advantages
- Formulas, formatting and multiple sheets in one file
- Opens in Excel, Google Sheets and LibreOffice Calc
- Preserves data types — dates, currencies, percentages
Limitations
- Overkill for machine-to-machine data exchange — that's CSV's job
- Databases and scripts generally can't ingest XLSX directly
- Macros (in the XLSM variant) are a common malware vector — plain XLSX is safer
How to open a Excel (XLSX) file
Microsoft Excel, Google Sheets (free, browser-based) and LibreOffice Calc (free, desktop) all open XLSX. To feed the data into a database, script or import form, convert the workbook to CSV.
Frequently asked questions
Is XLSX the same as Excel?
Yes. XLSX is the file format Microsoft Excel has used by default since Excel 2007, so an .xlsx file is an Excel spreadsheet. Google Sheets, LibreOffice Calc, Apple Numbers and WPS open it too.
What is the difference between XLSX and XLS?
XLS is the legacy binary format from Excel 2003 and earlier, limited to 65,536 rows. XLSX replaced it in 2007: it is an open XML-based format, holds over a million rows per sheet and is less prone to corruption. Save new files as XLSX.
How do I open an XLSX file without Excel?
Upload it to Google Sheets (free, in the browser), or open it in LibreOffice Calc (free, desktop) or Numbers on a Mac. On a phone, the free Google Sheets or Microsoft Excel apps open XLSX attachments.
Why won't my XLSX file open?
Common causes are an incomplete download, a password on the workbook, a very old Excel version (before 2007, without the compatibility pack), or a phone with no spreadsheet app installed. Try opening it in Google Sheets: if that also fails, the file is likely damaged.
Should I save my spreadsheet as XLSX or CSV?
Use XLSX while people are working on the file: it keeps formulas, formatting, data types and multiple sheets. Use CSV when the data is going into another system, such as a database, an import form, a script or an e-commerce platform, because CSV is the format every tool can read. Our CSV vs XLSX guide covers the trade-offs.