How to Open an XLSX File

What is an XLSX file?

.xlsx is the default spreadsheet format used by Microsoft Excel since Excel 2007, replacing the older binary .xls format. Structurally, an .xlsx file is actually a ZIP archive containing a set of XML files — one describing the workbook's sheets, one holding all the shared text strings, one per worksheet with its cell data, plus styling and metadata files. This is the same "Office Open XML" structure used by .docx (Word) and .pptx (PowerPoint).

That ZIP-based structure is exactly what the tool on this page reads directly: it opens the ZIP, decompresses the relevant XML parts using your browser's built-in decompression, and parses the cell data — all without any external spreadsheet library.

How to open an XLSX file on Windows

1. Double-click the file — it opens in Microsoft Excel if installed.
2. No Excel? Install the free LibreOffice Calc from libreoffice.org, which opens .xlsx files with strong compatibility.
3. Alternatively, upload it to Google Sheets (sheets.google.com) for free, browser-based editing.

How to open an XLSX file on Mac

1. Double-click the file to open it in Microsoft Excel if installed.
2. Without Excel, Apple Numbers (pre-installed on most Macs) opens and converts .xlsx files automatically.
3. LibreOffice Calc is also a free, cross-platform option available for Mac.

How to open an XLSX file on Android & iPhone

Android: The free Microsoft Excel app or Google Sheets app both open .xlsx files directly from Downloads, email attachments, or cloud storage.

iPhone: Tapping a .xlsx attachment offers to open it in the Excel, Numbers or Google Sheets app if installed, or gives a basic Quick Look preview otherwise.

XLSX vs XLS — what's the difference?

.xlsx is the modern format (Excel 2007+), an XML/ZIP-based structure that's more compact, more resistant to corruption, and easier for other software to read. .xls is the older binary format from Excel 97–2003, using a completely different internal structure. Modern Excel, LibreOffice and Google Sheets all open both, but a tool built specifically to parse XLSX's ZIP/XML structure — like the one on this page — can't read the older .xls binary format, since there's no shared structure between them at all.

Is it safe to open an XLSX file?

A plain .xlsx file itself can't contain macros — that's what the separate .xlsm extension is for, and Excel enforces the distinction. However, an .xlsx can still contain formulas that pull in external data or links, so treat one from an unknown source with the same caution as any other document: avoid enabling "Edit Content" or following embedded links you don't recognize. Viewing the raw cell data first, like the tool on this page does, is a safe way to check a file's contents without letting Excel evaluate any formulas.

Common XLSX file errors and how to fix them

"Excel cannot open the file because the file format or file extension is not valid"

Usually means the file is either corrupted, or was renamed to .xlsx from a different format without actually being converted. Try opening it with the tool on this page or another viewer to check what's actually inside; if it's genuinely corrupted, you'll need to get a fresh copy from the source.

File opens but shows "Protected View" or won't let you edit

Excel opens files downloaded from the internet or email in read-only Protected View by default as a safety measure. Click "Enable Editing" in the yellow bar at the top, but only if you trust the source.

Formulas show as text instead of calculating (e.g. "=SUM(A1:A5)")

Usually caused by the cell being formatted as Text before the formula was entered. Change the cell format to General or Number, then re-enter the formula.

Related file extensions

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