TrueType file signature
Magic number at the start of the file
A TrueType font starts with the sfnt version 00 01 00 00. Some older Apple fonts use the ASCII tag true instead. The same 00 01 00 00 value is why raw TrueType and some other sfnt files look alike at byte 0.
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 00 01 00 00, it is a TrueType file.
Signature variants
TrueType appears with more than one byte pattern. These all identify the same family:
| Hex signature | Offset | Note |
|---|---|---|
| 00 01 00 00 | 0 | TrueType outlines |
| 74 72 75 65 | 0 | 'true', older Apple TrueType |
Formats that use the 00 01 00 00 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.ttf
- hexdump -C -n 16 example.ttf
- file example.ttf
Windows (PowerShell)
- Format-Hex -Path example.ttf -Count 16
Python
- open("example.ttf","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 TrueType file signature?
TrueType files start with the hex bytes 00 01 00 00. 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.ttf on Linux or macOS, or Format-Hex -Path example.ttf -Count 16 in Windows PowerShell, and read the first bytes.
Can a file fake the TrueType signature?
Renaming a file does not change its bytes, so the extension can lie but the signature usually cannot. A genuine TrueType file has these exact bytes; a file with the wrong bytes is not really TrueType, whatever its name says.