AscendLab

Video tools

Subtitle Time Shifter

Free browser tool

Subtitle Time Shifter for SRT and VTT

Shift SRT or WebVTT subtitle timestamps forward or backward by seconds directly in your browser.

Subtitle time shifter
Shift every SRT or WebVTT timestamp forward or backward by seconds.
Shifted subtitle output
4 timestamps updated.
Quick answer

Use this tool when subtitle timing is consistently early or late across the whole file.

It adjusts every timestamp while keeping cue text and layout lines intact.

Best inputs

One subtitle file

Paste a complete SRT or WebVTT file for best context.

Known offset

Measure how many seconds the first cue needs to move.

Backup copy

Keep the original subtitle text until you review the output.

Subtitle shift method
The tool finds timestamp tokens and adds the selected offset.
Comma and dot millisecond formats are supported.
Cue text and numbering are left in place.
Negative results are clamped to zero.
Example, Assumption, and Limitation
Use the result as a practical estimate or transformation, then confirm edge cases for critical work.

Example

Enter 1.5 to delay every cue by one and a half seconds.

Assumption

The subtitle drift is a fixed offset, not a gradually changing timing problem.

Limitation

It does not stretch subtitles, translate text, or fix individual cue timing.

Common use cases
These pages are built for lightweight browser-side work, examples, and planning.

Late captions

Delay captions after an intro edit.

Early captions

Move subtitles earlier after trimming video start.

Course videos

Adjust captions for edited lessons.

Publishing QA

Quickly test subtitle sync fixes before upload.

Frequently asked questions

Can this fix subtitles that are too early or too late?

Yes. Enter a positive offset to move subtitles later or a negative offset to move them earlier.

Does it support SRT and VTT?

Yes. It shifts timestamps that use comma or dot millisecond separators.

Will negative times be preserved?

No. Timestamps are clamped at 00:00:00.000 or 00:00:00,000.

Does the subtitle text upload anywhere?

No. The shift runs locally in your browser.

Suggested workflow

Subtitle sync workflow

Inspect the video, shift the subtitle file, then convert subtitle format if needed.