Fix Subtitles That Are Out of Sync

Why subtitles go out of sync

The usual cause is a mismatch between the subtitle file and the video cut. The subtitles may have been made for a version with a different opening, a distributor logo, or a scene that your copy does not have. If your video starts two seconds later than the version the subtitles were timed for, every line will be two seconds early. The text itself is fine; only the timing is shifted.

A second cause is a player or conversion delay that applies to the whole file. Either way, the signature of a constant offset is the same: the error is the same size at the beginning, in the middle, and at the end. Check a line near the start and a line near the end. If both are off by the same amount, a single shift will fix the file.

How to measure the offset

Pick one line that is easy to hear, such as the first spoken sentence. Play the video and note the moment the line is actually spoken, then look at the timestamp of that line in the subtitle file. The difference is your offset.

Work out the direction carefully, because it decides the sign. If the subtitle appears before you hear the line, it is early, and you shift it later with a positive number. If the subtitle appears after you hear the line, it is late, and you shift it earlier with a negative number. For example, a subtitle timed at 00:01:10 for a line spoken at 00:01:08 is two seconds late, so you shift by -2.

Measure twice, at two different points in the video, before you shift. If the two measurements agree, you have a constant offset. If they do not, read the next section before shifting, because a single shift will not fix that file.

How to shift every SRT timestamp by the same amount

1. Play the video, pick one clearly spoken line, and note when it is spoken versus the timestamp of that line in the subtitle file.
2. Work out the shift: subtitles that appear before the line need a positive number, and subtitles that appear after the line need a negative number.
3. Open the Subtitle Time Shifter, paste the SRT, enter the shift in seconds, and shift the whole file at once.
4. Check the first and last lines against the video, then save the result as a new .srt file and keep the original unchanged.

Shifting only changes the timestamps. The text, cue order, and line breaks stay exactly as they were, and times that would go below zero are clamped to 00:00:00,000, so a large negative shift cannot produce a negative timestamp.

When a single shift will not fix the file

If the delay grows over the course of the video, the subtitles are drifting, not offset. Drift usually comes from a frame-rate difference between the subtitle timing and the video, and a constant shift can only fix one point: fix the start and the end will still be off, or the other way round. A drifting file needs re-timing, not a single shift.

A second trap is a file that is only wrong in one section, for example after a missing scene. Shifting the whole file would fix that section and break everything before it. In that case, split the file at the break, shift only the affected part, and rejoin the two halves.

If only some lines are wrong while the rest are right, the problem is in those cues themselves, not in the timing as a whole. Fix those lines individually instead of shifting the file.

Common questions

Do I shift by a positive or a negative number? Subtitles that appear before the line need a positive number, because their timestamps must move later. Subtitles that appear after the line need a negative number, because their timestamps must move earlier. A subtitle timed at 00:01:10 for a line spoken at 00:01:08 is two seconds late, so you shift by -2.

Will shifting change the subtitle text? No. Shifting only changes the timestamps. The text, cue order, and line breaks stay exactly as they were, and times that would go below zero are clamped to 00:00:00,000.