Subtitle file formats compared
SRT, WebVTT, SBV and ASS all store timed text, but they differ in syntax, styling and where they work. Here is the short version.
The quick comparison
All four formats hold the same core data: a start time, an end time and some text. The differences are in how timestamps are written and how much formatting the format allows.
| Format | Extension | Timestamp style | Styling | Positioning | Best for |
|---|---|---|---|---|---|
| SRT (SubRip) | .srt | 00:00:01,000 --> 00:00:04,000 | Minimal (basic tags like <i> and <b>, player-dependent) | No standard support | Maximum compatibility: desktop players, editors, YouTube, social platforms |
| WebVTT | .vtt | 00:00:01.000 --> 00:00:04.000 | CSS via ::cue, voice tags, classes | Yes (line, position, size, align cue settings) | Web video with the HTML5 <track> element |
| SBV (YouTube) | .sbv | 0:00:01.000,0:00:04.000 | None | None | Importing and exporting captions in YouTube Studio |
| ASS (Advanced SubStation Alpha) | .ass | 0:00:01.00 (in a Dialogue line) | Full: fonts, colors, outlines, shadows, animation, karaoke | Yes, precise per-line placement | Anime, fansubs, and any video that needs styled or placed text |
SRT: the safe default
SRT is a numbered list of cues with comma-separated milliseconds. It has almost no formatting, which is exactly why nearly every player, editor and upload form accepts it. If you are unsure which format to deliver, SRT is the one that rarely gets rejected.
WebVTT: the web standard
WebVTT starts with a WEBVTT header line, uses a period before the milliseconds, and is the format browsers read through the HTML5 <track> element. It adds cue settings for placement and lets you style captions with CSS. Most web players expect it.
SBV: YouTube's own format
SBV puts the start and end time on one line separated by a comma, and has no cue numbers or styling. You will mostly meet it when downloading or uploading captions in YouTube Studio. Outside YouTube, convert it to SRT first.
ASS: when you need real styling
ASS files are divided into sections for script info, styles and events, and support fonts, colors, outlines, exact placement and animation. Players such as VLC and mpv render it well, but browsers do not read it natively, so it is rarely the right choice for web delivery.
Which should you pick?
- Uploading to a social platform or sending to a client: SRT.
- Captioning video on your own website: WebVTT.
- Working inside YouTube Studio: SBV or SRT.
- Styled or positioned text in a video file or player: ASS.
Convert between them
Every conversion below runs in your browser, so your file is never uploaded.
Cite or link to this page
You are welcome to link to this reference from tutorials, documentation or forum answers. A plain link works:
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