Convert Subtitle Frame Rate (FPS)
Subtitles made for a 23.976 fps film but your video runs at 25 fps (or the other way round)? Convert the timing in one click.
The rate the subtitles were made for.
The rate of the video you play now.
🔒 Runs in your browser. Your files and text are not uploaded.
How to use the Subtitle FPS Converter
- Drop your subtitle file or paste its text.
- Enter the frame rate the subtitles were made for in the first box (often 23.976) and the frame rate of the video you are playing in the second box (often 25).
- Press Convert frame rate. The info line shows the scaling factor and where the last subtitle lands.
- Download the converted file and load it in your player.
Why frame rates make subtitles drift
A film shot at 24 frames per second (broadcast as 23.976) lasts longer than the same frames played at 25 frames per second. European (PAL) TV and many DVD and web releases speed the film up by about 4%, so a two-hour movie ends roughly 4 minutes 50 seconds earlier. Subtitles timed for the slower version then fall behind the picture more and more as the film goes on — at the start they look fine, an hour in they are minutes late.
The cure is to scale every timestamp by old fps ÷ new fps. For 23.976 → 25 fps that factor is 0.95904: a subtitle at 1:30:00 moves to 1:26:18.8. For 25 → 23.976 it is 1.04271.
Common conversions
| From | To | Factor | Typical situation |
|---|---|---|---|
| 23.976 | 25 | 0.95904 | NTSC/web-release subtitles used with a PAL (25 fps) copy |
| 25 | 23.976 | 1.04271 | PAL subtitles used with a 23.976 fps Blu-ray rip |
| 24 | 25 | 0.96000 | Cinema timing to PAL |
| 25 | 24 | 1.04167 | PAL timing to cinema speed |
| 23.976 | 24 | 0.99900 | Tiny 0.1% drift (about 6 s per hour) |
| 29.97 | 25 | 1.19880 | NTSC video converted to PAL |
You can type any value — the fields accept decimals such as 23.976, 29.97 or 59.94.
How to tell that frame rate is the problem
Frame-rate mismatches have a recognisable signature: the first lines match, and the error grows linearly to a few minutes by the end. Compare the last spoken line with its subtitle. If the ratio of the two run times is about 0.959 or 1.043, you have a PAL/film mismatch. If you only know the error at two points, the two-point sync tool computes the factor for you; if it comes out near one of the values above, use this tool to get the exact figure.
Frame-based subtitle formats
Some old formats such as MicroDVD .sub store frame numbers rather than times. Those files only make sense together with a frame rate, which is why the wrong rate causes drift in the first place. To get an SRT with real timestamps, convert it with the SUB to SRT converter, choosing the frame rate the file was made for, and then run it through this tool if you also need to change speed.
Frequently asked questions
Which frame rate do I enter in each box?
First box: the rate the subtitles were made for (usually the rate of the original release — 23.976 for most films and TV shows). Second box: the rate of the video you are actually watching (25 for many European releases and some downloads).
How do I find my video’s frame rate?
Open the file in VLC and choose Tools → Codec Information, or use MediaInfo. The “Frame rate” entry shows values like 23.976 or 25.000.
Will this fix a constant offset too?
No. Scaling only fixes drift. If the first line is also off, run the result through the timing shifter afterwards, or use the two-point sync tool to fix both at once.
What does the info line mean?
It shows the multiplication factor applied to every time stamp and where the last subtitle moves to, so you can sanity-check the result against your video length.
Does it change the text?
No. Only time codes are rewritten; text, formatting and styles are untouched.
Is it safe to use with confidential subtitles?
Yes. The conversion happens in your browser and nothing is uploaded.