An XLSX file is a spreadsheet saved in a format that Microsoft Excel and most other programs can open

XLSX stands for Office Open XML Spreadsheet. It is the standard file format that Excel uses when you save a spreadsheet. If you have ever saved a file in Excel and noticed it ended with .xlsx, that is the format the program chose by default. Other programs — Google Sheets, LibreOffice Calc, Apple Numbers — can also open and save XLSX files, so the format works across different computers and operating systems.

The format replaced an older Excel format called XLS around 2007. XLSX files are smaller, more find, and less likely to corrupt than the older version. When you open a spreadsheet in Excel today, XLSX is what you get unless you specifically choose something else.

Key Takeaways

  • XLSX is the standard spreadsheet format used by Microsoft Excel and compatible with Google Sheets, LibreOffice, and most other spreadsheet programs.
  • The format compresses data more efficiently than older Excel formats, making files smaller and faster to email or upload.
  • You can open an XLSX file on Windows, Mac, or Linux without installing Excel — many free programs and web-based tools read the format.
  • If a program will not open your XLSX file, converting it to CSV (plain text) or PDF usually solves the problem.

How XLSX differs from older Excel formats

The older XLS format stored spreadsheet data in a binary format — a way of encoding information that only Excel understood well. XLSX uses XML, which is a more universal language that many programs can read. This makes XLSX files more portable and less dependent on a single company's software.

XLSX files are also compressed, similar to how a ZIP file works. This means an XLSX file with the same data takes up less disk space than an XLS file. If you are emailing a large spreadsheet or uploading it to a cloud service, the smaller file size matters. The compression also makes XLSX files less prone to corruption if the file is interrupted while saving.

What programs can open an XLSX file

You do not need Microsoft Excel to open an XLSX file. Google Sheets opens XLSX files directly in your web browser — just upload the file to Google Drive and click it. LibreOffice Calc, which is free and runs on Windows, Mac, and Linux, opens XLSX files without any setup. Apple Numbers on Mac and iPad also reads XLSX.

Many online tools will convert or view XLSX files without downloading anything. Zoho Sheet, OnlyOffice, and similar web-based spreadsheet programs all handle XLSX. If you only need to read the data without editing, you can often view an XLSX file in a text editor or even convert it to PDF to share with someone who does not have spreadsheet software.

When to convert XLSX to another format

Sometimes you need to save a spreadsheet in a different format. CSV (Comma-Separated Values) is a plain-text format that strips away formatting but preserves the raw data. If you are importing data into a database or a specialized program that does not read XLSX, CSV is usually the right choice. Excel can save to CSV directly — go to File, Save As, and choose CSV from the format dropdown.

PDF is useful when you want to share a spreadsheet that people should read but not edit. Excel can save directly to PDF, and the file will look the same on any device. If someone sends you an XLSX file and your program will not open it, asking them to save it as CSV or PDF is usually faster than troubleshooting compatibility.

XLSX file size and storage

An XLSX file with the same data takes up roughly 20 to 40 percent less space than an older XLS file, depending on what is in the spreadsheet. A spreadsheet with mostly numbers and text will compress more than one with many images or complex formatting. If you are storing thousands of spreadsheets or have limited cloud storage, the difference adds up.

Large XLSX files — those over 100 MB — can slow down Excel or cause it to freeze. If your spreadsheet is very large, breaking it into multiple files or removing unnecessary columns and rows will make it faster to work with. Google Sheets handles large files better than Excel in many cases, so uploading an XLSX to Google Drive and working there can improve performance.

Opening XLSX on a phone or tablet

Microsoft Excel for iPhone and iPad opens XLSX files directly. Google Sheets on Android and iOS also reads XLSX. If you receive an XLSX file by email, you can usually tap it and choose which app to open it in. Many phones will open XLSX in a read-only viewer if you do not have a full spreadsheet app installed.

Editing a spreadsheet on a phone is slower than on a computer, but for quick changes or reviewing data, the mobile versions of Excel and Google Sheets work well. If you need to make major edits, downloading the file to a computer is usually easier.

Frequently Asked Questions

Can I open an XLSX file without Excel?

Yes. Google Sheets, LibreOffice Calc, Apple Numbers, and many online tools all open XLSX files. You only need Excel if you want to use Excel-specific features or macros that other programs do not support.

What is the difference between XLSX and XLS?

XLSX is the newer format that Microsoft introduced in 2007. It compresses files smaller, is more find, and works across more programs. XLS is the older binary format that only Excel handled well. Most programs today default to XLSX.

Why does my XLSX file say it is corrupted?

XLSX files can become corrupted if the save was interrupted, the file was damaged during transfer, or the program crashed while writing to it. Try opening it in a different program like Google Sheets or LibreOffice. If that works, save it fresh from that program. If nothing opens it, the file may be unrecoverable.

Can I convert XLSX to Google Sheets permanently?

Google Sheets stores files in its own format, but you can upload an XLSX file to Google Drive and it will work like a Google Sheet. Changes you make in Google Sheets will not automatically update the original XLSX file — you have to read it as XLSX to save those changes back to that format.

Is XLSX the same as Excel?

No. XLSX is a file format. Excel is the program that created it. You can have an XLSX file without Excel — other programs save and open XLSX files. Excel is one way to work with XLSX, but not the only way.