DDS file signature
Magic number at the start of the file · DDS
A DirectDraw Surface texture starts with the ASCII magic DDS followed by a space (0x20), then a 124-byte header describing the texture and its mipmaps.
What this magic number means
A magic number is a short, fixed run of bytes at a known position that tells a program what a file really is, no matter what the filename says. If a file starts with the bytes 44 44 53 20 (the text DDS ), it is a DDS file.
Formats that use the 44 44 53 20 signature
These file types in our database carry this signature:
How to check a file's signature
You can read the first bytes of any file yourself. The magic bytes are shown in hex, the same way this page lists them.
Linux & macOS
- xxd -l 16 example.dds
- hexdump -C -n 16 example.dds
- file example.dds
Windows (PowerShell)
- Format-Hex -Path example.dds -Count 16
Python
- open("example.dds","rb").read(4).hex()
In your browser
- Drop the file into the WhatFileType identifier, which reads the signature without uploading it.
Frequently asked questions
What is the DDS file signature?
DDS files start with the hex bytes 44 44 53 20 (DDS in ASCII). This magic number identifies the format regardless of the file's name or extension.
How do I check a file's magic number?
Open the file in a hex editor, or run a command such as xxd -l 16 example.dds on Linux or macOS, or Format-Hex -Path example.dds -Count 16 in Windows PowerShell, and read the first bytes.
Can a file fake the DDS signature?
Renaming a file does not change its bytes, so the extension can lie but the signature usually cannot. A genuine DDS file has these exact bytes; a file with the wrong bytes is not really DDS, whatever its name says.