PPT is the pre-2007 PowerPoint binary. 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 a PPT file on the way to becoming a PDF one.
What runs when a PPT file becomes PDF
LibreOffice 24.2, on a machine we rent and watch. Your PPT file is uploaded once, LibreOffice runs once, the PDF comes back, and neither file is kept. PPT 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 PPT into the PDF
The PPT page layout, exactly. LibreOffice renders your PPT 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 PPT document reads the same on a machine that has never had those fonts installed.
PPT tables, drawn as they were drawn. Borders, merged cells and column widths survive into the PDF because they are painted rather than re-described.
One PPT slide per PDF page, with the deck order intact.
What PPT to PDF costs you
Editability. A PDF is the end of the line: nobody downstream can change a sentence without going back to your PPT 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 PPT file knew about itself stops at the print stage. A program reading the PDF sees positioned glyphs and guesses the rest.
PPT speaker notes, animations and slide transitions. What lands in the PDF is the slide, not the performance. Measured on this pair: the notes are not in the file at all, which is the reassuring half of the story.
Where PPT and PDF files come from
PPT. PowerPoint wrote it before 2007, and it is an OLE2 binary. Decks of this age usually come out of an archive rather than off somebody desk, which is why converting one is generally the first step in reading an old presentation at all.
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 PPT file, convert it to Markdown instead and skip the reconstruction entirely.
PPT to PDF, measured rather than promised
Running PPT to PDF against the real engine with a real file, LibreOffice wrote 20,740 bytes of PDF in 1.1 seconds, machine otherwise idle. That is one PPT file on one day and not an average, which is why the number is given together with the file that produced it.
The PPT 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 PPT file, sent somewhere else
Other outputs the probe measured out of a PPT 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 PPT witness file.
PPT to HTML: 27,543 bytes in 1.5 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, PPT is the number 14 largest output of the 26 measured. The witness files differ, so this ranks the probe run and not your document.
ODT to PDF: 11,917 bytes in 1.1 seconds.
ODS to PDF: 12,884 bytes in 1.1 seconds.
ODP to PDF: 20,929 bytes in 1.3 seconds.
RTF to PDF: 11,917 bytes in 1.1 seconds.
CSV to PDF: 12,680 bytes in 1.0 seconds.
What we will not pretend about PPT to PDF
A PPT file over 25 MB is refused before the upload finishes rather than after it, so you do not wait for a rejection.
A PPT 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 PPT 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 PPT file at a time, chosen in the browser. There is nothing else to set up and nothing else on offer.
PPT to PDF: what people ask
What actually converts my PPT 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 PPT file is uploaded once, LibreOffice runs once, the PDF comes back, and neither file is kept afterwards.
How long does PPT to PDF take?
On the file the probe used, LibreOffice took 1.1 seconds and wrote 20,740 bytes of PDF. That is one real measurement on one real PPT file, not an average and not a promise about yours: a larger PPT takes longer, and past 90 seconds the run is stopped.
What do I lose going from PPT 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 PPT file. Sometimes that is exactly the point, and sometimes it is exactly the problem.
Is the PDF searchable afterwards?
Yes. The text in your PPT 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 PPT to PDF free?
There is a free allowance every month, and one PPT 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.