How to Sync Subtitles That Are Out of Sync
Updated 2026-06-21
If your subtitles are out of sync, the fastest fix is to shift every cue by a fixed offset: if captions appear two seconds early, add +2s to the whole track. When subtitles start in sync but drift further off as the video plays, a single shift won't help — you need a two-point sync that stretches the timing instead. The Subtitle Editor, Converter & Resync does both, entirely in your browser, with nothing uploaded.
Diagnose the problem first
Play the video with the subtitles and note how the lag behaves:
- Constant lag — every line is early or late by the same amount from start to finish. This is the common case after a frame-rate mismatch or a trimmed intro.
- Growing drift — lines are roughly in sync at the start but slip more and more toward the end. This usually means the subtitle file was timed for a different frame rate (for example a 23.976 fps file played at 25 fps).
Time how far off one early line is, and how far off one late line is. If both are off by the same amount, it's a constant lag. If the gap grows, it's drift.
Fix a constant lag with a fixed offset
- Drop your .srt, .vtt, .sbv, .ass, or .lrc file into the tool — the format is detected automatically.
- Enter the offset. Captions showing two seconds too early need +2s (push them later); captions a second late need -1s.
- Preview the shifted cues, then export.
The offset is applied to every cue's start and end together, so the on-screen duration of each line is preserved.
Fix drift with two-point sync
When the lag grows over time, pick two cues whose correct times you actually know — typically the first spoken line and a line near the end. Tell the tool what timestamp each one should land on, and it linearly stretches and offsets the entire track so both anchors hit exactly. Everything in between is corrected proportionally. This is the only reliable way to fix frame-rate drift that a flat shift can't touch.
Convert and clean up while you're there
Once the timing is right, you can export to a different format — SRT for most players, VTT for the web, LRC for synced lyrics, SBV or ASS as needed. The tool also runs a quality check against reading-speed presets (Netflix at 17 characters per second, BBC, or a relaxed social-video profile) and flags cues that are too fast, too short, overlap, or run past the line-length limit. A batch find-and-replace fixes a recurring misspelled name across every cue without retyping.
Why local matters
Subtitle files often carry an unreleased episode's full dialogue. Because everything here runs on your device, the captions never leave the tab — no upload, no account, no waiting on a server.
Ready to fix your captions? Open the Subtitle Editor, Converter & Resync and drop in your file.