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SRT Subtitle Shifter & Converter — Resync and Convert SRT ⇄ VTT

Subtitles a second or two ahead of the audio? Paste your SRT or VTT file — or upload it — and shift every timing at once by any number of seconds, including decimals like 2.5 or -1.25. You can also convert between SubRip (.srt) and WebVTT (.vtt) with a single click, then copy or download the fixed file. Everything runs in your browser, so your subtitles are read locally and never uploaded.

Everything runs in your browser. Files are read locally and never uploaded.

Or upload a subtitle file
seconds

Positive delays the subtitles (they appear later); negative moves them earlier. Decimals like 2.5 or -1.25 are fine.

Output format

SRT uses commas (00:00:01,000); WebVTT uses dots (00:00:01.000) and a WEBVTT header.

Your converted subtitles will appear here

Paste subtitle text or upload a .srt / .vtt file, then set a shift and output format.

How to use

  1. Paste your subtitle text into the box, or upload a .srt or .vtt file.
  2. Enter how many seconds to shift — positive to delay the subtitles, negative to move them earlier.
  3. Choose the output format: SRT or WebVTT.
  4. Check the parsed cue count and any warnings on the right.
  5. Click "Copy result" or "Download file" to save the corrected subtitles.

Features

  • Shift every cue by any offset, including decimal seconds, in one step
  • Convert between SRT (comma milliseconds) and WebVTT (dot milliseconds)
  • Robust parser handles HH:MM:SS,mmm, HH:MM:SS.mmm and short MM:SS.mmm timing
  • Negative times are clamped to 00:00:00 so cues never go below zero
  • Shows how many cues were parsed plus clear warnings for malformed blocks
  • 100% client-side with FileReader — subtitles are never uploaded to a server

Frequently asked questions

How do I fix subtitles that are ahead of or behind the audio?
Paste or upload the file, then type the offset in seconds. If the subtitles appear too early, use a positive value to delay them; if they lag behind, use a negative value. The tool applies the same shift to every cue and shows the result instantly.
What is the difference between SRT and WebVTT?
Both store timed subtitle text. SubRip (.srt) separates milliseconds with a comma (00:00:01,000) and numbers each cue, while WebVTT (.vtt) uses a dot (00:00:01.000) and begins with a WEBVTT header. WebVTT is the format used by HTML5 video, so converting SRT to VTT is common for the web.
Are my subtitle files uploaded anywhere?
No. Files are read in your browser with the FileReader API and all parsing, shifting and conversion happen locally in JavaScript. Nothing is sent to a server, so it is safe for private or unreleased content.
Can I use decimal or negative shifts?
Yes. You can enter values such as 2.5, 0.25 or -1.75. Positive values push subtitles later, negative values pull them earlier. Any timing that would become negative is clamped to 00:00:00.
What do the parse warnings mean?
Warnings flag blocks the tool could not fully understand — for example a block with no timestamp line, an unreadable time, or a cue whose end is before its start. Those blocks are reported so you can fix the source file; valid cues are still converted.
Does it keep my cue text and line breaks?
Yes. The text and line breaks inside each cue are preserved exactly. Only the timestamps are adjusted, and cues are renumbered for SRT output.