RTF is rich text that almost every word processor ever written can open. PDF is a frozen page layout with no heading structure a machine can rely on. LibreOffice sits between the two, and this page says exactly what happens to an RTF file on the way to becoming a PDF one.
What runs when an RTF file becomes PDF
LibreOffice 24.2, on a machine we rent and watch. Your RTF file is uploaded once, LibreOffice runs once, the PDF comes back, and neither file is kept. RTF to PDF is one of the 3649 pairs that engine was probed on with a real file, which is why it has a page here and why the pairs the probe could not prove do not.
What survives from the RTF into the PDF
The RTF page layout, exactly. LibreOffice renders your RTF file the way it would print it, so margins, columns, page breaks, headers and footers land in the PDF where the author put them.
Fonts, embedded in the PDF, so your RTF document reads the same on a machine that has never had those fonts installed.
RTF tables, drawn as they were drawn. Borders, merged cells and column widths survive into the PDF because they are painted rather than re-described.
Numbered and bulleted lists, footnotes and the RTF table of contents, all frozen into the PDF at their rendered positions.
What RTF to PDF costs you
Editability. A PDF is the end of the line: nobody downstream can change a sentence without going back to your RTF file. Sometimes that is exactly the point, and sometimes it is exactly the problem.
Structure a machine can use. PDF has no heading hierarchy, no list semantics and no table model, so everything the RTF file knew about itself stops at the print stage. A program reading the PDF sees positioned glyphs and guesses the rest.
Tracked changes and comments print into the PDF according to the RTF document settings, which is rarely what people expect the first time they try it.
Where RTF and PDF files come from
RTF. Almost everything can write it, and that is the point: an RTF is plain text you can open in a text editor and read. It was the interchange format before there was an open standard, and it survives in exports from software too old or too small to ship anything better.
If a model is going to read the PDF
Worth knowing before the PDF goes anywhere near an assistant: this is the wrong direction for that. A PDF is a set of positioned glyphs, and a model has to reconstruct the reading order before it can begin. If a machine rather than a person is going to read this RTF file, convert it to Markdown instead and skip the reconstruction entirely.
RTF to PDF, measured rather than promised
Running RTF to PDF against the real engine with a real file, LibreOffice wrote 11,917 bytes of PDF in 1.1 seconds, machine otherwise idle. That is one RTF file on one day and not an average, which is why the number is given together with the file that produced it.
The RTF to PDF verdict was reached by a format signature, meaning at least four bytes unique to the format were found at the right offset. Which check was used matters, because they do not all prove the same thing, and a status code of 200 proves nothing whatsoever about whether the PDF file has anything inside it.
The same RTF file, sent somewhere else
Other outputs the probe measured out of an RTF file, so the cost of choosing PDF can be read against something. Sizes do not compare across engines, because each family was probed with its own RTF witness file.
RTF to MD: 265 bytes in under a tenth of a second, verified by a pandoc round trip.
RTF to DOCX: 5,422 bytes in 1.1 seconds, verified by a format signature.
RTF to EPUB: 5,033 bytes in 0.1 seconds, verified by a pandoc round trip.
RTF to TXT: 263 bytes in under a tenth of a second, verified by reading the text back.
RTF to HTML: 3,985 bytes in 0.1 seconds, verified by a pandoc round trip.
RTF to ODT: 12,670 bytes in 1.2 seconds, verified by reading the internal type and finding a witness word.
Other ways into PDF, and what they measured
Among the published routes into PDF, RTF is the number 23 largest output of the 26 measured. The witness files differ, so this ranks the probe run and not your document.
CSV to PDF: 12,680 bytes in 1.0 seconds.
EPUB to PDF: 61,941 bytes in 1.9 seconds.
MOBI to PDF: 62,207 bytes in 1.9 seconds.
AZW3 to PDF: 62,065 bytes in 1.8 seconds.
HTML to PDF: 25,178 bytes in 1.9 seconds.
What we will not pretend about RTF to PDF
An RTF file over 25 MB is refused before the upload finishes rather than after it, so you do not wait for a rejection.
An RTF to PDF run that passes 90 seconds is killed, and the LibreOffice process is killed with it. A run left behind would sit on one of the machine's two cores until somebody noticed.
LibreOffice is serialised on purpose, one document at a time per worker, because each soffice instance takes 150 to 300 MB on a machine with 3.8 GB. Measured ceiling: 23 RTF conversions in flight and roughly 0.9 a second sustained. Past that the queue answers 429 rather than falling over, which was tested at 32 at once.
One RTF file at a time, chosen in the browser. There is nothing else to set up and nothing else on offer.
RTF to PDF: what people ask
What actually converts my RTF file to PDF?
LibreOffice does it, 24.2, on a machine we rent and watch. Not a browser trick and not somebody else service: the RTF file is uploaded once, LibreOffice runs once, the PDF comes back, and neither file is kept afterwards.
How long does RTF to PDF take?
On the file the probe used, LibreOffice took 1.1 seconds and wrote 11,917 bytes of PDF. That is one real measurement on one real RTF file, not an average and not a promise about yours: a larger RTF takes longer, and past 90 seconds the run is stopped.
What do I lose going from RTF to PDF?
The one to know about first: Editability. A PDF is the end of the line: nobody downstream can change a sentence without going back to your RTF file. Sometimes that is exactly the point, and sometimes it is exactly the problem.
Is the PDF searchable afterwards?
Yes. The text in your RTF file is written into the PDF as text, not as a picture of text, so it can be searched and copied. What the PDF does not have is structure: no headings, no list model, no table model. It reads well to a person and parses badly to a program.
Is RTF to PDF free?
There is a free allowance every month, and one RTF to PDF conversion costs half a credit against it. When the allowance runs out the tool says so and stops, rather than quietly handing you a worse PDF.