RTF file signature
Magic number at the start of the file · {\rtf1
Rich Text Format is plain text that always begins with the control word {\rtf1. Being text, it opens in any editor, but the {\rtf1 prefix is what applications key on.
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 7B 5C 72 74 66 31 (the text {\rtf1), it is a RTF file.
Formats that use the 7B 5C 72 74 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.rtf
- hexdump -C -n 16 example.rtf
- file example.rtf
Windows (PowerShell)
- Format-Hex -Path example.rtf -Count 16
Python
- open("example.rtf","rb").read(6).hex()
In your browser
- Drop the file into the WhatFileType identifier, which reads the signature without uploading it.
Frequently asked questions
What is the RTF file signature?
RTF files start with the hex bytes 7B 5C 72 74 66 31 ({\rtf1 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.rtf on Linux or macOS, or Format-Hex -Path example.rtf -Count 16 in Windows PowerShell, and read the first bytes.
Can a file fake the RTF signature?
Renaming a file does not change its bytes, so the extension can lie but the signature usually cannot. A genuine RTF file has these exact bytes; a file with the wrong bytes is not really RTF, whatever its name says.