TIFF file signature
Magic number at the start of the file · II*.
TIFF encodes its own byte order in the first two bytes: II for little-endian or MM for big-endian, followed by the number 42. Many camera raw formats, including Adobe DNG, are TIFF containers and share this header.
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 49 49 2A 00 (the text II*.), it is a TIFF file.
Signature variants
TIFF appears with more than one byte pattern. These all identify the same family:
| Hex signature | Offset | Note |
|---|---|---|
| 49 49 2A 00 | 0 | little-endian (Intel, II) |
| 4D 4D 00 2A | 0 | big-endian (Motorola, MM) |
Formats that use the 49 49 2A 00 signature
These file types in our database carry this signature:
It is also seen in: CR2, NEF, ARW.
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.tiff
- hexdump -C -n 16 example.tiff
- file example.tiff
Windows (PowerShell)
- Format-Hex -Path example.tiff -Count 16
Python
- open("example.tiff","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 TIFF file signature?
TIFF files start with the hex bytes 49 49 2A 00 (II*. 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.tiff on Linux or macOS, or Format-Hex -Path example.tiff -Count 16 in Windows PowerShell, and read the first bytes.
Can a file fake the TIFF signature?
Renaming a file does not change its bytes, so the extension can lie but the signature usually cannot. A genuine TIFF file has these exact bytes; a file with the wrong bytes is not really TIFF, whatever its name says.