How to use Subtitle Converter
Convert subtitle and caption files between SRT, WebVTT (VTT), and other formats instantly in your browser — no file uploads, no account needed. Paste your captions or upload the file, choose the target format, and download the converted result. The converter automatically rewrites timestamp delimiters, adds or removes the WebVTT header, and normalises line endings so the output works in every major video player and streaming platform.
- Upload your subtitle file (.srt, .vtt, .ass, or .ssa) or paste the raw caption text into the input box.
- Select the source format from the dropdown (or let the tool auto-detect it).
- Choose the target output format: SRT, WebVTT, or plain text.
- Click "Convert" — timestamp delimiters and headers are rewritten automatically.
- Review the output preview, then click "Copy" or "Download" to save the converted file.
Your data never leaves your device — 100% private processing.
SRT vs WebVTT vs ASS: format comparison
SRT (SubRip Text) is the most universally supported subtitle format, using a numeric sequence counter, a timestamp line, and one or more lines of caption text per cue. WebVTT (Web Video Text Tracks) is the W3C standard for HTML5 video; it requires a WEBVTT header on the first line and uses a dot as the millisecond delimiter in timestamps. ASS/SSA (Advanced SubStation Alpha) supports rich styling such as font, colour, position, and karaoke effects, making it common in anime fansubs, but it requires a compatible renderer and is not supported natively in HTML5 video.
| Format | Extension | Timestamp delimiter | Header required | HTML5 video | Styling support |
|---|---|---|---|---|---|
| SRT | .srt | Comma (HH:MM:SS,mmm) | None | Via JS only | Basic bold/italic |
| WebVTT | .vtt | Dot (HH:MM:SS.mmm) | WEBVTT (first line) | Native <track> | CSS cue styling |
| ASS/SSA | .ass / .ssa | Centiseconds (H:MM:SS.cs) | Script info block | No | Full typography |
Timestamp syntax details
SRT timestamp lines use a comma to separate seconds from milliseconds: 00:01:23,456 --> 00:01:25,789. WebVTT uses a dot in the same position: 00:01:23.456 --> 00:01:25.789, and may also omit the hours field for short videos (01:23.456 --> 01:25.789). The arrow separator (-->) is the same in both formats. A common conversion error is swapping the delimiter — a VTT file containing comma-delimited timestamps will not render correctly in a browser <track> element. This tool rewrites all delimiters to match the target format automatically.
Platform compatibility and use cases
HTML5 video players (<video> with <track kind="subtitles">) require WebVTT; SRT is not parsed natively by browsers. YouTube accepts both SRT and VTT via its caption upload interface. Vimeo prefers VTT. Most desktop media players (VLC, mpv, MPC-HC) read SRT natively. FFmpeg can burn-in subtitles from SRT or ASS files during video encoding. When publishing to multiple platforms, maintain a master SRT and convert to VTT for web, keeping the SRT for YouTube and desktop distribution.
Glossary
- SRT (SubRip Text)
- A plain-text subtitle format with a sequential cue number, a "HH:MM:SS,mmm --> HH:MM:SS,mmm" timestamp line, and caption text per block.
- WebVTT (VTT)
- The W3C Web Video Text Tracks format; starts with a "WEBVTT" header line and uses dot-delimited timestamps (HH:MM:SS.mmm). Natively supported by HTML5 <track>.
- Cue
- A single timed caption entry — comprising a start time, an end time, and the text to display during that interval.
- ASS/SSA
- Advanced SubStation Alpha — a feature-rich subtitle format supporting per-line font, colour, and position styling, widely used in anime releases.
- Millisecond delimiter
- The character separating the seconds value from milliseconds in a subtitle timestamp: a comma in SRT (e.g. 00:01:05,300) and a dot in VTT (e.g. 00:01:05.300).
Related reading
Frequently Asked Questions
Why use Subtitle Converter?
- Rewrites timestamp delimiters automatically so converted files play correctly in every player
- Converts SRT to WebVTT for native HTML5 <track> embedding without manual reformatting
- Strips ASS/SSA styling tags on conversion to plain SRT or VTT for broad compatibility
- Normalises line endings so converted VTT files parse without errors in Chrome or Firefox
Common use cases
- Convert an SRT subtitle file to WebVTT to add native captions to an HTML5 video element
- Change the subtitle format of an anime release from ASS to SRT for use in VLC
- Convert a WebVTT caption file to SRT before uploading to YouTube's caption interface
- Reformat a transcription service's SRT output to VTT for a custom video player
- Convert captions from a corporate webinar recording to the format required by a company LMS
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