How to fix out-of-sync subtitles

Out-of-sync subtitles usually fall into two buckets:

• the whole file is early or late by a fixed amount
• the subtitle drift changes over time

This first version of the site is built for the first case.

Step 1: confirm the problem type

If every subtitle line is late by about the same amount, a time shifter is enough.

If the sync gets worse over time, the file probably needs deeper retiming or re-export from your editor.

Step 2: measure the offset

Check one clear spoken line and compare:

• when the person actually starts speaking
• when the subtitle appears

If subtitles appear 1.2 seconds late, shift the whole file by -1200 ms.

If subtitles appear 0.8 seconds early, shift the whole file by 800 ms.

Step 3: apply a global shift

Use the Subtitle Time Shifter and enter:

• positive numbers to delay captions
• negative numbers to move them earlier

Step 4: test multiple points

After shifting, check:

• the beginning
• the middle
• the end

If all three are close, you fixed a constant offset. If not, the file may be drifting rather than simply shifted.

Common causes

• the intro of the video was trimmed after subtitles were exported
• subtitles were downloaded from a different video cut
• captions were generated before the final edit

Related tools

• Subtitle Time Shifter
• VTT to SRT Converter