What does "out of sync" mean?

It means subtitles appear earlier or later than the spoken dialogue. Shifting all timestamps by a fixed amount corrects this.

How do I figure out the right offset?

Note when a specific line is spoken in the video and when the subtitle appears. The difference in seconds is your offset. If subtitles are 2 seconds early, enter +2.

What is the difference between positive and negative values?

Positive (+) delays subtitles (shifts later). Negative (-) advances them (shifts earlier). If subtitles appear before the dialogue, use a positive value.

Can I adjust by milliseconds?

Yes. Use decimals, such as 0.5 for 500 milliseconds.

What happens if a timestamp goes below zero?

By default, any subtitle that would start before 0:00 is clamped to zero. The result shows how many cues were clamped.

Are my files sent to a server?

No. Everything is processed in your browser. Files are never uploaded to any server and are released when you close the tab.

Can I change the output format at the same time?

Yes. You can keep the original format or convert to SRT, VTT, or SMI while adjusting the sync.

Is there a file size limit?

Up to 10MB on desktop and 5MB on mobile. Most subtitle files are well under these limits.

Does the dialogue text change?

No. Only the start and end timestamps are shifted. The text stays identical.

Does it handle Korean subtitles?

Yes. UTF-8 and CP949 (EUC-KR) encoding are auto-detected, so Korean subtitles are processed without issues.

Subtitle Sync Adjuster

Subtitles out of sync? Shift all timestamps forward or backward by any amount. Works with SRT, VTT, and SMI files.

Adjust subtitle timing

Drop files here or choose files

SRT, VTT, SMI, SAMI · Up to 1 files

Subtitles appearing too early or too late? Drop your SRT, VTT, or SMI file here and shift all timestamps forward or backward by any amount. Enter the offset in seconds and the tool applies it with millisecond precision.