What is a .cab file? (CAB)

A CAB (cabinet) file is Microsoft's compressed archive, used to bundle files for Windows installers, drivers and updates. You rarely open one by hand: Windows setup and driver tools read it, but 7-Zip can extract one if you need to.

What is a .cab file used for?

A .cab packs multiple files with good compression, and it is the container Windows uses inside setup programs, driver packages and system updates.

Because installers and INF-driven driver setups consume it automatically, you seldom open a CAB directly. When you do need the files, 7-Zip or the built-in expand command extracts them.

It is purely an archive, so like a ZIP it holds files but runs nothing on its own.

How to open a .cab file

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

Windows

File Explorer (view)
7-Zip
expand command

macOS

The Unarchiver
7-Zip

Linux

cabextract
7-Zip

Web

Not natively; extract locally

How to convert a .cab file

You can convert a .cab file to ZIP, 7Z using a conversion tool or the export menu of an app that opens it.

.cab file signature (magic bytes)

Programs recognise a .cab file by the bytes at the start of the file, not by its name. These are the signatures for CAB. For a full breakdown, see the CAB file signature page.

Hex signature	Offset	Note
4D 53 43 46	0	'MSCF'

See the full magic-numbers reference for every format.

Frequently asked questions

What is a .cab file?

How do I open a CAB file?

Double-click to browse it in File Explorer, or extract it with 7-Zip. From a command prompt, expand file.cab -F:* target-folder pulls the files out.

How do I extract a driver from a CAB?

Extract the CAB with 7-Zip or the expand command, then point Device Manager's Update Driver, Browse my computer at the extracted folder so it can find the .inf file.

Related formats

Sources

Details on this page were checked against authoritative references:

Wikipedia: Cabinet (file format)