reStructuredText is the markup Python documentation is written in. Markdown is markup you can read with your own eyes, and the format language models read best. pandoc sits between the two, and this page says exactly what happens to an RST file on the way to becoming an MD one.
What runs when an RST file becomes MD
pandoc in two passes, on a machine we rent and watch. Your RST file is uploaded once, pandoc runs once, the MD comes back, and neither file is kept. RST to MD 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 RST into the MD
The heading hierarchy. pandoc parses the RST file into its own document tree and writes that tree out as MD, so a level two heading is still a level two heading and not merely bold text.
Tables, rebuilt in MD syntax rather than screenshotted. That is the difference between a table a machine can read and a picture of one, and it is the whole reason to send an RST file through pandoc rather than through a printer.
Lists from the RST file, nesting included, plus code blocks, block quotes and links, all re-expressed in MD.
Images: pandoc extracts them out of the RST file into a working directory and re-embeds them in the MD, so nothing ends up pointing at a file that no longer exists.
Document metadata from the RST file, which the JSON intermediate keeps and which a plain text pass would silently drop.
What RST to MD costs you
Fine typography. Named RST styles, colours and font choices collapse into plain emphasis, because plain emphasis is all MD has. For most people this is the reason to run the conversion, not a regret about it.
If a model is going to read the MD
This is the direction that helps a language model, and it is the reason this site exists. An RST file carries structure, and MD is the one output on this list that hands that structure over in a form a model already reads: a heading is two characters, a table is pipes, a list is a dash. No part of the context window goes on describing layout, because after the RST file has been through pandoc there is no layout left to describe.
RST to MD, measured rather than promised
Running RST to MD against the real engine with a real file, pandoc wrote 266 bytes of MD in 0.1 seconds, machine otherwise idle. That is one RST file on one day and not an average, which is why the number is given together with the file that produced it.
The RST to MD verdict was reached by a pandoc round trip, meaning the output was read back by pandoc and had to still contain a witness word planted in the source, which proves the content travelled and not merely the container. 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 MD file has anything inside it.
The same RST file, sent somewhere else
Other outputs the probe measured out of an RST file, so the cost of choosing MD can be read against something. Sizes do not compare across engines, because each family was probed with its own RST witness file.
RST to DOCX: 10,105 bytes in 0.1 seconds, verified by a pandoc round trip.
RST to EPUB: 5,036 bytes in 0.1 seconds, verified by a pandoc round trip.
RST to TXT: 264 bytes in 0.1 seconds, verified by reading the text back.
RST to HTML: 4,018 bytes in 0.1 seconds, verified by a pandoc round trip.
RST to RTF: 687 bytes in 0.1 seconds, verified by a pandoc round trip.
RST to ODT: 7,537 bytes in 0.1 seconds, verified by a pandoc round trip.
Other ways into MD, and what they measured
Among the published routes into MD, RST is the fifth largest output of the 8 measured. The witness files differ, so this ranks the probe run and not your document.
IPYNB to MD: 382 bytes in 0.1 seconds.
CSV to MD: 114 bytes in 0.1 seconds.
JSON to MD: 266 bytes in under a tenth of a second.
HTML to MD: 371 bytes in under a tenth of a second.
ODT to MD: 277 bytes in 0.1 seconds.
What we will not pretend about RST to MD
An RST file over 25 MB is refused before the upload finishes rather than after it, so you do not wait for a rejection.
An RST to MD run that passes 60 seconds is killed, and the pandoc process is killed with it. A run left behind would sit on one of the machine's two cores until somebody noticed.
32 of the 935 pairs probed in the family that serves RST to MD failed, and this pair is not one of them. They fail for reasons worth knowing: a writer that cannot carry what the document is made of, or output the engine could not read back. They are counted here rather than hidden, because a pair that fails quietly is worse than one that fails loudly.
pandoc never writes the MD through a TeX engine here, and it never writes PDF at all: the eleven engines it would need are not on this machine and a TeX distribution weighs several gigabytes. Anyone who wants a PDF out of an RST file goes through LibreOffice or calibre, both of which genuinely can.
One RST file at a time, chosen in the browser. There is nothing else to set up and nothing else on offer.
RST to MD: what people ask
What actually converts my RST file to MD?
pandoc does it, in two passes, on a machine we rent and watch. Not a browser trick and not somebody else service: the RST file is uploaded once, pandoc runs once, the MD comes back, and neither file is kept afterwards.
How long does RST to MD take?
On the file the probe used, pandoc took 0.1 seconds and wrote 266 bytes of MD. That is one real measurement on one real RST file, not an average and not a promise about yours: a larger RST takes longer, and past 60 seconds the run is stopped.
What do I lose going from RST to MD?
The one to know about first: Fine typography. Named RST styles, colours and font choices collapse into plain emphasis, because plain emphasis is all MD has. For most people this is the reason to run the conversion, not a regret about it.
Are the tables in my RST file still tables in the MD?
Yes. pandoc reads the RST tables into its own document tree and writes them back out in MD syntax, so what you get is a table a machine can parse rather than a picture of one.
Is RST to MD free?
There is a free allowance every month, and one RST to MD 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 MD.