Quick answer
- An XLSX file is an Office Open XML SpreadsheetML workbook. Microsoft Excel has used .xlsx as its default format for new workbooks since Excel 2007. Current desktop Excel can open, edit, and save XLSX files; Excel for the web and Microsoft’s mobile Excel apps can also open them.
- On Windows or macOS, open the file with a current desktop version of Microsoft Excel; it supports opening, editing, and saving XLSX. In a browser, use Excel for the web to open the workbook. On a phone or tablet, use Microsoft’s mobile Excel app. Older Excel versions and third-party applications may support fewer features, so inspect formulas, formatting, charts, images, links, and connections after opening. If Office opens the file in read-only Protected View, review its source before enabling editing.
- An XLSX file cannot store VBA code or Excel 4.0 macro sheets, but it can contain external data connections and workbook links. An unfamiliar source or automatically updated link may be harmful; Microsoft presents security warnings so you can decide whether to enable external content. Files from the internet, email attachments, or unsafe locations can also contain malicious content or malformed structures intended to attack a parser. Keep an untrusted workbook in Protected View and enable editing or connections only after confirming that its source and content are trustworthy.
XLSX File: How to Open, Check, and Convert an Excel Workbook
XLSX is standardized by ISO/IEC 29500 and ECMA-376. Technically, it is a ZIP package organized under the Open Packaging Conventions. Its main spreadsheet parts are normally under the xl directory: workbook.xml describes the workbook, the worksheets directory contains sheets, and separate parts hold styles, calculation order, charts, images, and other content. An XLSX workbook can represent text and numeric tables, formulas and functions, external data connections, charts, and images. Complete interoperability depends on whether the receiving application and version support the workbook’s markup and features.
For a working copy that must retain workbook structure and supported Excel features, keep XLSX. To preserve VBA or Excel 4.0 macro content, use XLSM; renaming a file to .xlsx does not convert or preserve macros. Converting XLSX to CSV keeps only the displayed text and values from the active sheet. Other sheets, formatting, graphics, and objects are lost, and displayed formulas may become text. Conversion to other formats can also lose data, formatting, or functionality, so check the result against the original workbook.
Open a file
On Windows or macOS, open the file with a current desktop version of Microsoft Excel; it supports opening, editing, and saving XLSX. In a browser, use Excel for the web to open the workbook. On a phone or tablet, use Microsoft’s mobile Excel app. Older Excel versions and third-party applications may support fewer features, so inspect formulas, formatting, charts, images, links, and connections after opening. If Office opens the file in read-only Protected View, review its source before enabling editing.
On Windows or macOS, open the file with a current desktop version of Microsoft Excel; it supports opening, editing, and saving XLSX. In a browser, use Excel for the web to open the workbook. On a phone or tablet, use Microsoft’s mobile Excel app. Older Excel versions and third-party applications may support fewer features, so inspect formulas, formatting, charts, images, links, and connections after opening. If Office opens the file in read-only Protected View, review its source before enabling editing.
For a working copy that must retain workbook structure and supported Excel features, keep XLSX. To preserve VBA or Excel 4.0 macro content, use XLSM; renaming a file to .xlsx does not convert or preserve macros. Converting XLSX to CSV keeps only the displayed text and values from the active sheet. Other sheets, formatting, graphics, and objects are lost, and displayed formulas may become text. Conversion to other formats can also lose data, formatting, or functionality, so check the result against the original workbook.
File safety
An XLSX file cannot store VBA code or Excel 4.0 macro sheets, but it can contain external data connections and workbook links. An unfamiliar source or automatically updated link may be harmful; Microsoft presents security warnings so you can decide whether to enable external content. Files from the internet, email attachments, or unsafe locations can also contain malicious content or malformed structures intended to attack a parser. Keep an untrusted workbook in Protected View and enable editing or connections only after confirming that its source and content are trustworthy.
Do not open the file when its source, double extension, or actual contents do not match what you expected.
Converters
For a working copy that must retain workbook structure and supported Excel features, keep XLSX. To preserve VBA or Excel 4.0 macro content, use XLSM; renaming a file to .xlsx does not convert or preserve macros. Converting XLSX to CSV keeps only the displayed text and values from the active sheet. Other sheets, formatting, graphics, and objects are lost, and displayed formulas may become text. Conversion to other formats can also lose data, formatting, or functionality, so check the result against the original workbook.
Work from a copy, then compare image quality, metadata, and layout after conversion.
Frequently asked questions
What is an XLSX file and what information can an XLSX workbook contain?
An XLSX file is an Office Open XML SpreadsheetML workbook. It can contain numeric and text tables, formulas or functions, external data connections, charts, and images.
How can I open and edit an XLSX file on Windows or macOS?
Use a current desktop version of Microsoft Excel. It can open, edit, and save XLSX workbooks. Older versions or third-party applications may not support every feature.
How can I open an XLSX file on a phone, tablet, or web browser?
Use Microsoft’s mobile Excel app on a phone or tablet, or Excel for the web in a browser. Feature support can differ from desktop Excel, so check important workbook content.
What is the difference between an XLSX file and an XLSM file for macros?
Standard XLSX cannot store VBA code or Excel 4.0 macro sheets. Use XLSM when those macros must be retained; changing only the filename extension is not a conversion.
What will be lost when I convert an XLSX file to CSV?
CSV retains only the displayed text and values from the active worksheet. Other sheets, formatting, graphics, and objects are lost, and displayed formulas may be converted to text.
Why does an XLSX file open in Microsoft Office Protected View?
Office uses read-only Protected View for files from the internet, email attachments, unsafe locations, and files that fail validation. Enable editing only after confirming the source and content are trustworthy.
Can external data connections and workbook links in an XLSX file be unsafe?
Yes. XLSX cannot hold VBA macros, but it may contain external connections and workbook links. Do not enable unfamiliar sources or automatic link updates unless you trust them.
What should I check when an XLSX file is damaged or will not open normally?
Do not bypass Protected View or security warnings merely to force it open. Confirm the source, retain the original, and remember that an abnormal package structure may be malicious as well as damaged.
Can I open an XLSX file without installing desktop software?
Yes. Excel for the web can open an XLSX workbook in a browser. Check important formulas, formatting, charts, images, links, and connections because feature support can differ from desktop Excel.
Does opening an XLSX file successfully mean its data and links are trustworthy?
No. Successful opening shows that the application could process the workbook, not that its data, external connections, or workbook links are trustworthy. Verify the source and inspect important content before enabling editing or external updates.
Related formats
Sources
Media Types Registry: application/vnd.openxmlformats-officedocument.spreadsheetml.sheet · IANA
ECMA-376 Office Open XML File Formats · Ecma International
XLSX Transitional (Office Open XML), ISO 29500 and ECMA-376 · Library of Congress
Excel (.xlsx) Extensions to the Office Open XML SpreadsheetML File Format · Microsoft
File formats that are supported in Excel · Microsoft
Excel formatting and features that are not transferred to other file formats · Microsoft
Block or unblock external content in Office documents · Microsoft
What is Protected View? · Microsoft