tigtools

Subtitle Frame Rate Converter

Subtitles that start in sync and drift further out over the film were usually made for a different frame rate. Choose both rates and the timings are scaled to match.

Runs in your browser No sign-up

ms

Milliseconds; negative makes subtitles appear earlier. 1000 ms = 1 second.

or drop it here. The file stays on your device.

How to use it

  1. Open an .srt or .vtt file or paste the subtitles.
  2. Choose the frame rate the subtitles were made for and the frame rate of your video.
  3. Optionally add a shift if the first line is still early or late.
  4. Check the preview and download the retimed file.

How it works

A subtitle file made for a 25 fps release of a film (common in Europe) and played with a 23.976 fps release of the same film drifts: the film runs about 4 % slower, so subtitles appear progressively too early. Retiming multiplies every timestamp by source fps ÷ target fps, so a line shown at a given frame of the film stays at that frame. NTSC rates are used as exact fractions (24000/1001, 30000/1001, 60000/1001).

The shift is applied after scaling, for a constant offset at the start. Times are rounded to whole milliseconds. Cue text, numbering and WebVTT settings are kept; the output format can be the same as the input or converted.

Retiming fixes drift caused by a frame-rate difference only. If subtitles are out of sync by different amounts in different places, the video was edited differently (for example a different cut or ad breaks), and no single factor can fix that.

Examples

25 fps subtitles on a 23.976 fps video

A line at 01:00:00,000 moves to 01:02:33,750; a line at 00:00:10,000 moves to 00:00:10,427.

23.976 fps subtitles on a 25 fps video

The reverse: every time is multiplied by 0.959, so a two-hour film's last line moves almost five minutes earlier.

Frequently asked questions

How do I know which frame rates to choose?

Media players show the video's frame rate in their file information. If subtitles are fine at the start and about 4 % off at the end, the pair is usually 25 and 23.976 fps.

Will this fix subtitles that are always 2 seconds late?

That is a constant offset, not a frame-rate problem. Keep both frame rates equal and enter -2000 ms as the shift.

Is the frame rate stored in the subtitle file?

No. SRT and WebVTT use times in milliseconds, which is why a file made for one release can drift with another.

Privacy

Your subtitle file is read and retimed in your browser. It is not uploaded or stored.