Convert subtitles from 25 to 29.97 fps
Subtitles from a PAL TV episode used with an NTSC-speed version. Only needed when the NTSC version actually runs at a different speed — many conversions keep the duration and need no change.
Move subtitles by a fixed amount when every line is off by the same delay.
Seconds (2.5), milliseconds (1500ms) or a time (00:00:02,500). Subtitles appear too early → Later.
For subtitles that drift. Pick two cues far apart and enter when each should appear.
Rescale times when the subtitle was made for a video with a different frame rate.
The file open now is part 1 / language 1.
Cues
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Output preview
What the conversion does
Converting from 25 to 29.97 fps multiplies every subtitle time by 25 ÷ 29.97 = 0.834167. The subtitles become earlier by 16.58 % of their time, so the change is zero at the start and largest at the end. The exact NTSC rates are used (23.976 = 24000/1001, 29.97 = 30000/1001).
Drift between 25 and 29.97 fps
| Subtitle time | After conversion | Difference |
|---|---|---|
| 00:10:00 | 00:08:20,500 | −1 min 39 s |
| 00:30:00 | 00:25:01,500 | −4 min 58 s |
| 00:45:00 | 00:37:32,250 | −7 min 28 s |
| 01:00:00 | 00:50:03,000 | −9 min 57 s |
| 01:30:00 | 01:15:04,500 | −14 min 55 s |
| 02:00:00 | 01:40:06,000 | −19 min 54 s |
A 120-minute film timed at 25 fps runs 19 min 54 s shorter at 29.97 fps.
How to convert subtitles from 25 to 29.97 fps
- Open the subtitle file. Drop the subtitle file that drifts on the tool.
- Check the frame rates. “Subtitle made for” is set to 25 fps and “Video plays at” to 29.97 fps.
- Convert. Click Convert frame rate, then compare a line near the end with the video.
- Save. Download in SRT, VTT, ASS or TXT.
Other frame-rate conversions
Background: why subtitles drift between frame rates. Not sure of the rates? Use two-point sync — it detects the ratio for you.
FAQ
How much do subtitles drift between 25 and 29.97 fps?
16.58 % of the running time: 1 min 39 s after 10 minutes and 9 min 57 s after an hour.
What is the conversion factor from 25 to 29.97 fps?
Every time is multiplied by 25 ÷ 29.97 = 0.834167. A subtitle at 01:00:00 moves to 00:50:03,000.
How do I know this is the right fix?
If the subtitles are close at the start and the error grows steadily, it is a speed mismatch. If the error is the same everywhere, use Shift instead.