Convert subtitles from 23.976 to 24 fps
A small 0.1 % difference, but over a two-hour film it adds up to about 7 seconds — enough to make the last scenes feel off. Common when mixing digital cinema and home-video sources.
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 23.976 to 24 fps multiplies every subtitle time by 23.976 ÷ 24 = 0.999001. The subtitles become earlier by 0.10 % 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 23.976 and 24 fps
| Subtitle time | After conversion | Difference |
|---|---|---|
| 00:10:00 | 00:09:59,401 | −0.6 s |
| 00:30:00 | 00:29:58,202 | −1.8 s |
| 00:45:00 | 00:44:57,303 | −2.7 s |
| 01:00:00 | 00:59:56,404 | −3.6 s |
| 01:30:00 | 01:29:54,605 | −5.4 s |
| 02:00:00 | 01:59:52,807 | −7.2 s |
A 120-minute film timed at 23.976 fps runs 7.2 s shorter at 24 fps.
How to convert subtitles from 23.976 to 24 fps
- Open the subtitle file. Drop the subtitle file that drifts on the tool.
- Check the frame rates. “Subtitle made for” is set to 23.976 fps and “Video plays at” to 24 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 23.976 and 24 fps?
0.10 % of the running time: 0.6 s after 10 minutes and 3.6 s after an hour.
What is the conversion factor from 23.976 to 24 fps?
Every time is multiplied by 23.976 ÷ 24 = 0.999001. A subtitle at 01:00:00 moves to 00:59:56,404.
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.