Runs in your browser, no upload

Subtitle Timing Shift Resync Captions in Seconds

Drop an SRT or VTT file, enter how far the captions are off, and every timestamp moves earlier or later by that amount. This fixes captions that appear a fixed few seconds too early or too late through the whole video, the usual result of trimming an intro or re-encoding. The file is processed on this page and never uploaded.

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Paste or drop the file

SRT and VTT are both accepted. Drag the file into the box or paste its text. The format is detected from the content and preserved in the output.

Set the offset and shift

Enter the delay in seconds or milliseconds. A positive value moves captions later, a negative value moves them earlier. Timestamps that would fall below zero are clamped to 00:00:00.

Copy or download

Download the corrected file under the original name and drop it next to your video, or copy the text back into your editor or upload form.

How to tell whether a shift will fix it

Play the video and compare a line of dialogue near the beginning with its caption, then do the same near the end. If the captions are late by about the same amount in both places, say two seconds at minute one and two seconds at minute fifty, you have a constant offset and a shift is exactly the right repair. This is what happens when a few seconds of intro are cut from the video after the subtitles were made, when a broadcast recording starts slightly before or after the subtitle file assumes, or when a re-encode adds a short delay at the start.

If the error grows over time, correct at the start and twenty seconds off by the end, the subtitle file was made for a video running at a different frame rate or speed. A shift will line up one point and leave the rest wrong. That case needs the timings stretched by a ratio, which is a different operation that this tool does not perform. A subtitle editor with a frame rate conversion or a two-point synchronisation feature is the right tool there.

Finding the right offset

Pick a line that is easy to recognise, such as the first word spoken after a silence. Pause the video when it is spoken and note the time. Open the subtitle file and find the same line; the difference between the two times is your offset. If the caption time is larger than the video time, the captions are late and you need a negative value to pull them earlier; if the caption time is smaller, enter a positive value to push them later.

Most players accept a tenth of a second of error without the viewer noticing, so working to the nearest hundred milliseconds is usually enough. Apply the shift, play the same spot again, and adjust once more if needed. Because nothing is uploaded, running the tool three or four times costs nothing but a few seconds.

What the tool changes and what it leaves alone

Only the timing lines are touched. For SRT that means every HH:MM:SS,mmm --> HH:MM:SS,mmm line; for VTT the same with a full stop, including files that omit the hours. Cue numbers, cue identifiers, the WEBVTT header, NOTE and STYLE blocks, cue settings after the timing, and the caption text itself are written back exactly as they came in. The output is the same format as the input, so a VTT stays a VTT.

All of this runs in your browser. The file is read locally, adjusted in memory and offered for download. We do not receive it, do not keep it and do not ask you to sign in.

When the subtitle file is the real problem

Sometimes the timings are off in irregular ways because the captions were typed by hand or auto-generated by a platform with poor alignment. Shifting cannot repair that. In such cases it is often faster to make a fresh transcript from the audio: upload the video on the video transcription page and Transcrify returns timestamped, speaker-labelled text in your browser. 10 transcriptions of up to 3 hours each are free and need no account, and a free account can download the result as SRT, VTT, ASS or TXT with timings taken directly from the audio.

Frequently asked questions

Is the subtitle file uploaded?

No. The shift is applied by a script inside your browser. The file never leaves your computer and nothing is stored on our side.

Which direction is positive?

A positive offset moves every caption later, so it appears further into the video. A negative offset moves captions earlier. If your captions show up before the words are spoken, use a positive value.

The captions drift more and more as the video goes on. Will this help?

No. A growing error means the subtitle file was made for a different frame rate or playback speed, and the timings need to be stretched rather than shifted. Use a subtitle editor that offers frame rate conversion or two-point synchronisation for that.

What happens to cues that would start before zero?

They are clamped to 00:00:00,000. If the end time of such a cue is also below zero, the cue would be unplayable, so check the first few cues after a large negative shift.

Can I shift only part of the file?

Not with this tool; the offset is applied to every cue. If only the second half is off, split the file in a text editor, shift that part, and join the halves again.

Shift your subtitles now

Go back up, drop the SRT or VTT, enter the offset and download the corrected file. It is done in your browser in less time than it takes to read this sentence.

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