What is a .pptx file and how do I open it?

PPTX is the PowerPoint presentation format: a zipped bundle of slides, text, images and animations. It is the standard for slide decks and opens in PowerPoint, Google Slides and LibreOffice Impress.

What is a .pptx file used for?

A PPTX holds each slide's layout, text, images, charts, transitions and speaker notes as compressed XML.

It replaced the binary PPT in 2007 and is now the shared language of slide decks across every major presentation app.

To share a deck that cannot be edited, people export it as a PDF.

What opens a .pptx file?

The .pptx format opens in the following apps, grouped by operating system. If one app does not work, try another from the same list.

Windows

PowerPoint
LibreOffice Impress
Google Slides

macOS

PowerPoint
Keynote
LibreOffice Impress

Linux

LibreOffice Impress
OnlyOffice
Google Slides

Web

Google Slides
Office on the web

Open a .pptx file step by step

Confirm the file really is a .pptx. Drop it into the WhatFileType identifier, which reads its signature in your browser without uploading anything.
On Windows, open it with PowerPoint or LibreOffice Impress.
On Mac, use PowerPoint or Keynote.
On Linux, try LibreOffice Impress or OnlyOffice.
Still stuck? Convert the .pptx to PDF, which opens more widely.

Why can't I open my .pptx file?

Almost always because no installed app understands PPTX. Install one of the apps above, or convert the file to a format your existing software already reads. If double-clicking opens the wrong program instead of nothing at all, the file association is set to the wrong app rather than the file being broken.

The other possibility is that the file is not really a .pptx at all. Drop it into the file identifier to check it by its bytes instead of its name. Nothing is uploaded.

How to convert a .pptx file

You can convert a .pptx file to PDF, PNG, JPG using a conversion tool or the export menu of an app that opens it.

What is the .pptx file signature (magic bytes)?

A .pptx file starts with the hex bytes 50 4B 03 04, which read as PK.. in ASCII. Programs identify PPTX by those bytes, not by the filename, so a renamed file still gives itself away.

These are the documented signatures for PPTX. For a full breakdown, see the ZIP file signature page.

Documented magic-byte signatures for the .pptx format
Hex signature	Offset	ASCII	Note
50 4B 03 04	0	PK..	ZIP header (Office Open XML)

See the full magic-numbers reference for every format.

Frequently asked questions