Subtitle format converter
Convert SRT, WebVTT, SBV, and ASS input up to 5 MiB locally with strict cue validation and a 10 MiB output limit.
Subtitles stay in the browser. Styling, positioning, and some metadata are not preserved; invalid or blank input produces no download.
How to use this tool
Convert SRT, WebVTT, SBV, and ASS files up to 5 MiB locally while strictly validating cue timing and text.
Convert video subtitle files between SRT, WebVTT (VTT), ASS, and plain transcript text. Adjust global timestamp sync delays and clean up formatting for Premiere, Final Cut, or YouTube.
💡 3 Quick Steps to Get Started
Upload your .srt / .vtt file or paste raw subtitle lines into the input area.
Choose target format (SRT, VTT, or pure text) and optionally apply a timestamp millisecond shift.
Save your clean, syntactically valid subtitle file ready for video editing or YouTube closed captions.
When it helps
Detect or select the source and output SRT, WebVTT, SBV, or ASS except the same format; blank or malformed subtitles never succeed.
How it works
Times are parsed as integer milliseconds, every cue must start before it ends and contain text, and ASS output uses centisecond precision.
Worked example
Decode a Big5 SRT file and export UTF-8 WebVTT; one reversed or empty cue causes the entire file to be rejected.
Limits and data handling
Input over 5 MiB or output over 10 MiB is rejected. Cue timing and text are the supported contract. WebVTT settings/metadata and ASS styles/positioning are normalized or lost, so this is not full-fidelity conversion.
Subtitle files and text are not uploaded or stored. Analytics excludes cue text, filenames, formats, sizes, encodings, and raw errors.
Subtitle Formats (SRT/VTT/ASS), Timecode Sync & WebVTT Guide
1. Subtitle Symbology: SRT vs. WebVTT vs. ASS Formats
1. SRT (SubRip): Universally supported plain text subtitles using comma-delimited millisecond timestamps (`00:00:01,000`).
2. WebVTT (W3C Standard): Native HTML5 video track format featuring period-delimited timestamps (`00:00:01.000`), custom CSS styling, cue positioning, and voice tags.
3. ASS (SubStation Alpha): Advanced rendering format specifying rich coordinate typography and animated styling.
2. Precision Millisecond Timecode Offset Synchronization
When video edits introduce audio-sync drift, our conversion engine executes atomic millisecond arithmetic across all timestamp blocks, reconciling cue boundaries cleanly.
3. UTF-8 Normalization and Zero-Upload Guarantee
Legacy subtitle encodings (ANSI, Big5, Shift-JIS) are normalized to standard UTF-8 without ever dispatching media scripts over the network.
Feedback
How can we improve this tool?
Send a suggestion or bug report for this tool.
FAQ
What inputs does Subtitle format converter accept?
One file or edited input up to 5 MiB and output up to 10 MiB: SRT, WebVTT, SBV, or ASS. Encodings are UTF-8, UTF-16LE, UTF-16BE, Big5, Shift_JIS, and EUC-KR; a BOM takes precedence.
How does Subtitle format converter produce its result?
The browser decodes, parses, validates, and renders the subtitle locally. Download requires at least one valid cue and non-empty output.
What limitations apply to Subtitle format converter?
Input over 5 MiB or output over 10 MiB is rejected. Cue timing and text are the supported contract. WebVTT settings/metadata and ASS styles/positioning are normalized or lost, so this is not full-fidelity conversion.
How does Subtitle format converter handle data?
Subtitle files and text are not uploaded or stored. Analytics excludes cue text, filenames, formats, sizes, encodings, and raw errors.
