Subtitle shifter

Subtitle Shifter — Resync SRT & VTT Timing Free

Out-of-sync subtitles are almost always one constant offset: the captions were made for a version of the video with a different start point, an added intro, or a trimmed opening. You do not need to re-time every cue, you need to slide them all by the same amount. That is exactly what this tool does.

Subtitle shifter (resync SRT / VTT)

Shift by (seconds)Later (captions appear too early)

Runs in your browser. Nothing is uploaded — your files never leave your device.

Quick answer

To resync subtitles, paste your SRT or VTT above, enter the offset in seconds, positive if captions appear too early, negative if too late, and download the shifted file. Every timestamp moves by the same amount, the format is preserved, and the whole thing runs in your browser with no upload.

How to shift subtitle timing

1
Paste or pick your subtitle file
SRT and VTT both work, and the output keeps the same format. The file is processed locally.
2
Work out the offset
Find one line you can match to the video. If the caption shows 2 seconds before it is spoken, shift by +2. If it shows 2 seconds after, shift by −2. Decimals like 1.5 are fine.
3
Download the shifted file
Every cue moves by the same offset (never below zero). Load it in your player and spot-check the first and last minute.

Why subtitles drift out of sync

The usual cause is a version mismatch: the subtitle file was timed against a cut of the video with a different beginning, a channel intro, an ad bumper, or a trimmed cold open. Every cue is then wrong by the same constant amount, which is why one global shift fixes it.

A different problem is progressive drift, where captions start in sync and slowly fall behind. That comes from a frame-rate mismatch, not an offset, and a constant shift cannot fix it. If the error grows over time, you need the subtitle re-timed against the right frame rate or regenerated from the video.

Avoiding sync problems in the first place

Sidecar subtitle files can drift because they live separately from the video and every edit invalidates them. Burned-in captions cannot: the text is part of the picture. For short-form social content, burned-in is also simply what performs, most viewers watch muted.

Wavcut generates captions from your clip on-device and burns them in with word-level timing, so the sync is exact by construction and there is no file to shift. For web video where you need sidecar files, generate captions as the last step, after the edit is locked.

Frequently asked questions

Which direction should I shift?

If captions appear before the words are spoken, shift positive (later). If they appear after, shift negative (earlier). Match one line, apply the difference, and spot-check.

Does shifting work for both SRT and VTT?

Yes. The tool detects the format and outputs the same one, with all timestamps moved by your offset.

Can I shift by fractions of a second?

Yes, any decimal works, e.g. 0.3 or −1.25. Subtitle timestamps have millisecond precision.

My captions drift more and more over time. Will this fix it?

No. Progressive drift is a frame-rate mismatch, not a constant offset. A shift fixes files that are uniformly early or late; drift needs re-timing or regeneration.

Is my file uploaded to shift it?

No. The shift runs in your browser and the file never leaves your device.

How do I never deal with subtitle sync again?

Burn captions into the video. Wavcut transcribes on-device on iPhone and burns word-timed captions into the export, so there is no sidecar file to fall out of sync.