SRT (SubRip Subtitle) is the most widely used subtitle format. It's a plain text file containing subtitle entries with sequence numbers, timestamps in HH:MM:SS,mmm format, and subtitle text. SRT files are compatible with virtually all media players, video editors, and streaming platforms including VLC, YouTube, Netflix, and Prime Video.

The easiest method is to find a clear audio cue in your video (like a door slam, gunshot, or a character starting to speak) and note the exact time it occurs. Then find the corresponding subtitle entry and calculate the difference. You can also use the Anchor Adjustment feature in this tool — simply specify which subtitle entry should appear at which exact time, and the tool calculates the offset automatically.

Common causes include: (1) Different frame rates between the video source and subtitle source (e.g., 23.976 fps vs 25 fps), causing gradual drift. (2) Subtitles ripped from a different version of the movie (theatrical vs director's cut). (3) PAL vs NTSC speed differences (4% speed difference). (4) Ads or intro segments removed from the video but not the subtitles. (5) Incorrect starting offset applied during subtitle creation.

For gradual drift, use the Progressive Increment option in Advanced Options. If your subtitles start in sync but become progressively off by, say, 3 seconds by the end, set a small progressive increment per entry. Alternatively, you can use the Anchor Adjustment on two different entries to calculate both the base offset and the drift rate. For frame-rate-related drift (PAL/NTSC), a conversion factor of 23.976/25 = 0.959 (or 25/23.976 = 1.043) is often needed.

Milliseconds provide finer precision — 1 second = 1000 milliseconds. For most subtitle sync issues, adjustments between 100ms and 3000ms are typical. Use milliseconds when you need precise lip-sync accuracy (e.g., 350ms). Use seconds for larger, rougher adjustments. This tool supports both units and allows negative values (to make subtitles appear earlier) and positive values (to make them appear later).

Yes! Use the Range Limit fields in Advanced Options to specify which entries should be affected. For example, if only entries 50–120 need adjustment, set the range accordingly. Entries outside the range will keep their original timestamps. This is useful when only a specific scene or chapter is out of sync.

Yes, absolutely. All processing happens locally in your browser using JavaScript. Your SRT files and content never leave your device — nothing is uploaded to any server. This tool is completely free to use with no registration, no ads, and no limitations on file size or number of uses.