CHD File

What are CHD files and how to open them

Are you having problems opening a CHD file or are you simply curious about its contents? We're here to explain the properties of these files and provide you with software that can open or handle your CHD files.

What is a CHD file?

A .CHD file is a MAME Compressed Hard Disk Image file.

MAME Compressed Hard Disk Image files serve as compressed disk-image containers developed by the MAME project. They store exact copies of mass-storage media such as hard drives, CD-ROMs, DVDs, or LaserDiscs, that were used in arcade machines and related systems. These files provide an efficient way to archive and access large media dumps without needing raw, uncompressed copies.

These disk-image containers are created and manipulated using the official MAME tool called chdman. The raw media data is divided into fixed-size blocks called hunks. Each hunk is compressed independently, so only the currently needed portion of the image must be decompressed, which helps performance when reading large emulated disks. The format supports multiple compression algorithms within a single file - up to four different codecs in modern versions - so that different types of data (e.g. audio tracks) can use the best compression method. Creating these images is fully lossless: a properly made compressed image can be converted back into an identical raw image.

Files using this format begin with the ASCII signature MComprHD at byte offset zero. The header that follows uses big-endian encoding and includes fields such as format version, logical size of the data, compression types used, and one or more checksums (for example SHA-1 of the raw data and parent file if applicable) to verify integrity.

How to open CHD files

Important: Different programs may use files with the CHD file extension for different purposes, so unless you are sure which format your CHD file is, you may need to try a few different programs.

While we have not verified the apps ourselves yet, our users have suggested two different CHD openers which you will find listed below.

Last updated: August 31, 2026

Various apps that use files with this extension

These apps are known to open certain types of CHD files. Remember, different programs may use CHD files for different purposes, so you may need to try out a few of them to be able to open your specific file.

Help us help others

File.org helps thousands of users every day, and we would love to hear from you if you have additional information about CHD file formats, example files, or compatible programs. Please use the links below or email us at submit@file.org to discuss further.