Every Subtitle Format YouTube Accepts, and What It Ignores

Most people upload an SRT to YouTube because it is the file they have. YouTube actually accepts sixteen subtitle formats, treats them differently from one another, and throws away more of your file than you probably expect.

The list, grouped the way YouTube groups it

Basic formats carry timing and text and nothing else: SubRip (.srt), SubViewer (.sbv or .sub), MPsub (.mpsub), LRC (.lrc) and Videotron Lambda (.cap), the last of which is mainly used for Japanese subtitles.

Advanced formats can carry some presentation: SAMI (.smi or .sami), RealText (.rt), WebVTT (.vtt), TTML (.ttml) and DFXP (.ttml or .dfxp), which YouTube reads as TTML.

Broadcast formats are there for anyone arriving from television workflows: Scenarist Closed Caption (.scc), EBU-STL (.stl), Caption Center (.tds), Captions Inc (.cin), Cheetah (.asc or .cap) and NCI (.cap).

Your SRT styling is discarded

This is the part worth knowing before you spend time on it. YouTube says of SubRip and SubViewer that only basic versions are supported and no style information is recognised.

So italic tags, font colours and anything else you put inside an SRT are read as decoration and dropped. The words and the timings are what arrive. If you have been styling SRT files for YouTube, that work has not been reaching anyone.

WebVTT does slightly better. YouTube describes its support as an initial implementation, with positioning supported and styling limited to bold, italic and underline. So if placement genuinely matters on a video, WebVTT is the format that can express it, which the guide to caption positioning goes into. TTML and DFXP support both styling and positioning, and are the route worth taking if you are coming from a professional subtitling tool that already exports them.

ASS and SSA are not on the list

Advanced SubStation Alpha, the format most fansubbing and typesetting work lives in, is absent. YouTube will not take it. A styled ASS file has to become something else before it can be uploaded, and the styling does not survive that trip, because the formats YouTube does accept either ignore style entirely or support far less than ASS expresses.

The ASS to SRT converter handles the conversion and is direct about the cost. If the styling was decorative you lose nothing that matters. If it was carrying meaning, positioning that separates two speakers, or a sign translated in place, then converting genuinely loses information and it is better to know that before rather than after.

A caveat about our own SBV converter

Worth saying plainly: SubViewer is on YouTube's supported list. So if you downloaded an .sbv file from YouTube Studio and your only goal is to put it back on YouTube, you do not need to convert anything.

The SBV to SRT converteris for taking that file somewhere else, into an editor, another platform, or a client handoff, where SRT is the format that gets accepted. Converting for YouTube's sake alone would be work for nothing.

What to actually upload

For most creators, SRT remains the right answer. It is accepted everywhere, not only on YouTube, and since YouTube discards styling anyway there is nothing to gain from a richer format unless you specifically need positioning.

Reach for WebVTT when placement matters and the video is going to the web as well. Reach for TTML or DFXP if a subtitling tool already produces them and you want styling preserved. Convert away from ASS because you have no choice.

Whichever you pick, the wording is the part that decides whether the captions are any good, and that is worth more attention than the container. Generate a track in the caption generator, read it, and check the line lengths with the validator before you export.