PSD file signature
Magic number at the start of the file · 8BPS
Photoshop documents begin with 8BPS, the Adobe Photoshop signature, followed by a version number (1 for PSD, 2 for the large-document PSB variant).
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 38 42 50 53 (the text 8BPS), it is a PSD file.
Formats that use the 38 42 50 53 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.psd
- hexdump -C -n 16 example.psd
- file example.psd
Windows (PowerShell)
- Format-Hex -Path example.psd -Count 16
Python
- open("example.psd","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 PSD file signature?
PSD files start with the hex bytes 38 42 50 53 (8BPS 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.psd on Linux or macOS, or Format-Hex -Path example.psd -Count 16 in Windows PowerShell, and read the first bytes.
Can a file fake the PSD signature?
Renaming a file does not change its bytes, so the extension can lie but the signature usually cannot. A genuine PSD file has these exact bytes; a file with the wrong bytes is not really PSD, whatever its name says.