What Is RTF? How Rich Text Format Works

You may not hear about RTF much, but you have probably handled it many times: in the "Export" menu of an old program, as the default save format of TextEdit on a Mac, or as the "safest option" when moving a document between word processors. Rich Text Format describes formatting such as bold, italic, fonts, colors and tables using plain text characters. This article explains how RTF was born, what an RTF file looks like inside, where it shines and where it falls short, and what to watch for when converting it.

What is RTF?

RTF is a text-based format developed by Microsoft to move documents between different programs and operating systems. It is not a binary format like DOC: open an RTF file in Notepad and you can read your text, interleaved with backslash commands. But unlike HTML, it was not designed to be written by hand. Its purpose is to let one program read a document produced by another, formatting included.

One common confusion is worth clearing up first: the "rich text" option in email clients and web forms is usually a generic term for formatted text and is often HTML under the hood. RTF, the subject of this article, is a specific file format with the .rtf extension and its own syntax.

A short history

RTF was developed in the mid-to-late 1980s by Richard Brodie, Charles Simonyi and David Luebbert of the Microsoft Word team. The first RTF reader and writer shipped in 1987 with Word 3.0 for Macintosh, implementing RTF 1.0. Over the next twenty years the format grew alongside Word:

After 1.9.1, Microsoft stopped enhancing the RTF specification. According to the Library of Congress format description, Microsoft states that features introduced in Word 2010 and later will not be preserved when saved as RTF. In short, RTF is still supported but no longer evolving.

What is inside an RTF file?

RTF is built on three elements:

• Groups: sections enclosed in curly braces { }. A formatting change made inside a group ends when the group closes.
• Control words: letter sequences starting with a backslash, such as \b (bold) or \fs24 (font size in half-points; 24 means 12 pt). They can take a numeric parameter: \b1 turns bold on and \b0 turns it off.
• Control symbols: a backslash followed by a single non-letter character, such as \~ (non-breaking space) or \'e9 (a character from the code page, in hexadecimal).

A simple RTF document looks like this:

{\rtf1\ansi\ansicpg1252\deff0
{\fonttbl{\f0 Times New Roman;}}
{\colortbl;\red200\green0\blue0;}
\f0\fs24 This is a {\b bold} word and some {\cf1 red} text in a caf\'e9.\par
}

The file opens with {\rtf1, followed by the character set (\ansi) and the code page (\ansicpg1252, the Western European Windows code page). The font table (\fonttbl) and color table (\colortbl) are declared at the top and referenced by number in the text. \par ends a paragraph. The rest of the document holds section settings, headers and footers, paragraphs and tables; the Library of Congress notes that RTF treats tables as a kind of paragraph.

Non-ASCII characters can be written in two ways. The older method uses hexadecimal escapes such as \'e9 to refer to a character in the declared code page (E9 is "é" in code page 1252). The method added in RTF 1.5 uses Unicode control words such as \u305?: the number gives the character's Unicode value (305 is the Turkish dotless "ı"), and the character after it is a fallback for readers without Unicode support. RTF does not store text in a Unicode encoding such as UTF-8; the file itself is usually 7-bit ASCII.

Where is RTF used?

• Moving documents between programs: transferring formatted text between different word processors or operating systems.
• Report output from software: many business and industry applications produce formatted reports as RTF without depending on Word, because generating RTF is far simpler than generating DOCX.
• The clipboard: RTF is one of the common formats used when formatted text is copied on Windows and macOS.
• Simple editors: WordPad and TextEdit use RTF by default.

Strengths and weaknesses

A note on security: RTF cannot carry macros, but it is not risk-free. Records compiled on Wikipedia show RTF files being used in attacks through template injection and embedded OLE objects, with related flaws in old WordPad versions and in Word patched in 2017 and 2015. Treat RTF files from unknown sources with the same care as any other document.

Which programs open RTF?

Microsoft Word, LibreOffice Writer, Apple Pages, TextEdit and WPS Office can open and save RTF. WordPad, long the default RTF editor on Windows, is no longer included in current versions of Windows 11, so you will need Word or LibreOffice there. The Library of Congress also noted that RTF files could not be opened in the web and tablet versions of Word. Google Docs can import RTF and download documents as RTF.

Common problems and how to fix them

Accented or non-Latin characters look wrong

If the generating program declared the wrong code page, or used hex escapes from a different code page instead of Unicode control words, characters get swapped: a Turkish "ı" shows up as "ý" and "ş" as "þ", the classic sign of code pages 1254 (Turkish) and 1252 (Western European) being mixed up. Opening the file in Word or LibreOffice and saving it as DOCX is the easiest way to fix the source.

The file is much larger than expected

RTF usually stores images as hexadecimal text rather than binary, which roughly doubles the image data. For documents with images, DOCX or PDF produce much smaller files.

Formatting changes between programs

Each program supports a different subset of RTF and ignores control words it does not recognize. If the appearance must be exact, share the final version as a PDF.

Tips for converting RTF files

On our converter, RTF files are uploaded to our server, processed with LibreOffice and deleted within 30 minutes. Conversions between RTF, DOCX, DOC and PDF run directly with no intermediate step, so page layout, headers and footers, tables and list numbering are preserved.

• RTF to Word is the best option for editing output from legacy software and shrinking the file size.
• RTF to PDF locks down an appearance that otherwise varies between programs.
• RTF to TXT strips every control word and leaves only readable text.
• When using Word to RTF, remember that post-Word 2010 features (newer chart types, some layout options) may have no RTF equivalent.
• If you need a formatted document from plain text, TXT to RTF carries the text over paragraph by paragraph. RTF produced from sources such as HTML and Markdown also keeps bold text, headings, lists and tables through LibreOffice's RTF exporter.

Frequently Asked Questions

What is the difference between RTF and DOCX?

RTF describes formatting with control words embedded in plain text and has not changed since 2008. DOCX is a current, ZIP-based standard made of XML parts. DOCX supports more features and is far smaller for documents with images.

Can an RTF file contain macros?

No, RTF has no macro language. Embedded OLE objects and template references can still be abused, so stay careful with RTF files from unknown sources.

Is RTF still supported?

Yes, Word and other word processors still open and save RTF. But the last version of the specification, 1.9.1, was published in March 2008 and Microsoft no longer develops the format.

How do I open an RTF file on Windows 11?

On versions without WordPad, open it with Word, LibreOffice Writer or WPS Office. If you only need to read it, converting it to PDF and viewing it in a browser also works.

Why do special characters break in RTF?

Usually because the program that created the file declared the wrong code page. Programs that write Unicode control words avoid the problem entirely.

Sources

• Library of Congress: Rich Text Format (RTF) Version 1.9.1
• Wikipedia: Rich Text Format (history and security, secondary source)
• LibreOffice