What Is a .PUB File?

Microsoft Publisher Document (.pub)

Overview

A .pub file is a Microsoft Publisher document: a page-layout file for flyers, brochures, newsletters, greeting cards, labels and other print pieces, where text boxes and pictures are placed freely on a page rather than flowing like a Word document. Publisher has shipped with some Office editions since 1991 and is aimed at small businesses and home users rather than professional designers.

The format is the main reason the files are a nuisance: only Publisher opens .pub with full fidelity, Publisher has never existed for macOS, and Microsoft has announced the application's retirement from Microsoft 365 in October 2026. Anyone with .pub files should expect to convert them.

Technical Specifications

• MIME Type: application/x-mspublisher
• File Extension: .pub
• Category: Document
• Container: OLE2 compound document (the same binary container as .doc, .xls and .msi)
• Developer: Microsoft
• Introduced: 1991 (Publisher 1.0); format revised with Publisher 98, 2000, 2003 and 2007
• Magic bytes: D0 CF 11 E0 A1 B1 1A E1

Identification

00000000  d0 cf 11 e0 a1 b1 1a e1  00 00 00 00 00 00 00 00  |................|

The OLE2 header alone says only "a Microsoft compound document". Inside, a stream named Contents and a Quill storage (Publisher's text engine) identify the file as Publisher; the CLSID in the root entry is specific to Publisher as well. The .pub extension is also used by a few unrelated things, including public keys from some tools, so the content matters.

File Structure

Publisher stores pages, text boxes, pictures, tables and their formatting as a tree of OLE streams. The Quill storage holds text and typography in a format shared with Publisher's ancestor codebase; Contents holds the page objects; embedded pictures live as separate streams. Microsoft has not published a specification, which is why third-party support is thin: the only open implementation, libmspub, was reverse-engineered.

History and Development

Publisher 1.0 appeared in 1991 as an inexpensive desktop-publishing tool for Windows, positioned below Aldus PageMaker and QuarkXPress. It joined Office in 1996 and has been included in the Professional and some Microsoft 365 editions since. The file format changed with Publisher 98 and again with 2002 and 2003, after which it stayed stable; a Publisher 2003 file opens in Publisher 2021.

In 2024 Microsoft announced that Publisher will no longer be supported after October 2026 and will be removed from Microsoft 365; perpetual-licence copies keep working but receive no updates. The recommended path is to recreate layouts in Word, PowerPoint or Designer, which is a tacit admission that .pub was never a durable format.

Common Use Cases

• Small-business marketing: flyers, menus, brochures, business cards
• Community publications: church bulletins, club newsletters, school notices
• Labels, certificates and greeting cards from Publisher's templates
• Mail-merge pieces such as postcards and envelopes
• Archived print jobs that a print shop was sent a .pub for

How to Open a PUB File

With Publisher

• Microsoft Publisher (Windows only), included in Microsoft 365 Business Standard, Office Professional and some older suites. This is the only way to edit a .pub with everything intact.
• Microsoft 365 web apps do not include Publisher, and there is no mobile version.

Without Publisher

• LibreOffice Draw (Windows, macOS, Linux): opens .pub through the libmspub filter. Text, images and basic layout usually survive; master pages, some fonts and effects may not. Free, and the best non-Microsoft option.
• Online converters (Zamzar, CloudConvert, PDF2Go and others): upload the .pub, download a PDF. Fine for a one-off if the content is not confidential.
• Ask the sender for a PDF. Publisher exports PDF natively, and for a layout file that is the right thing to share anyway.

On macOS

No native option. LibreOffice Draw, an online converter, or Publisher inside a Windows virtual machine.

Checking what you have

file brochure.pub
# brochure.pub: Composite Document File V2 Document, ... Name of Creating Application: Microsoft Publisher

How to Convert a PUB File

From Publisher (best quality)

• To PDF: File, Export, Create PDF/XPS, or Save As with PDF selected. Choose Commercial Press quality for print, Standard for screen. This is how print shops expect to receive Publisher work.
• To images: Save As PNG, JPEG or TIFF (one page at a time) or Export, Pack and Go.
• To Word: Save As does not offer .docx. Copy the text boxes into Word, or export PDF and open the PDF in Word, which reconstructs editable text reasonably well.
• To PowerPoint: likewise via PDF, or copy and paste objects.

Without Publisher

• LibreOffice: open the .pub in Draw, then File, Export As, PDF, or File, Save As ODG (editable) or export SVG. From the command line:

soffice --headless --convert-to pdf brochure.pub

• Online converters for PDF, DOCX or images when fidelity matters less than convenience.

Planning for Publisher's retirement

Export every important .pub to PDF now, while a copy of Publisher is still available, and keep the PDF as the reference. For documents that must remain editable, rebuild them in Word (for text-heavy pieces), PowerPoint (for freely placed objects) or a dedicated layout tool such as Affinity Publisher or Scribus; none of them imports .pub directly, so the PDF and the extracted images are the raw material.

Advantages

• Easy page layout for non-designers, with templates and wizards.
• Included with some Office editions, so no extra purchase for those users.
• Mail merge and print-shop export built in.

Limitations

• Publisher-only: no macOS, web or mobile version, and third-party support is partial.
• Undocumented binary format, reverse-engineered by one open-source library.
• Application being retired in 2026, with no official successor format.
• Not a professional layout format: print shops prefer PDF, and designers use InDesign, Affinity Publisher or Scribus.

Related Formats

• PDF: what every .pub should be exported to.
• DOC and MSI: other files built on the same OLE2 container, which is why they share a signature.
• DOCX: the Word format most Publisher content ends up rebuilt in.
• PPTX: Microsoft's own suggested home for free-form layouts.