Changed the video frame rate? Upload an SRT or VTT file and rescale all timestamps proportionally to the new FPS.
Your subtitles are processed locally in your browser. No upload required.
FPS conversion is needed when subtitles are not just consistently early or late, but drift further out of sync as the video plays. This often happens when a subtitle file was created for a different version of the video, for example subtitles made for 24 FPS while the new video runs at 25 FPS.
A frame-rate conversion changes the entire timeline, not just a single starting point. A 24 FPS video and a 25 FPS video do not necessarily have the same duration when the footage has been sped up or slowed down. That is why a simple time shift is not enough: the subtitles may look close at the beginning, but after a few minutes the error becomes obvious.
The converter does not guess. It uses a simple mathematical scale factor. Every start and end time is multiplied by the ratio between the original FPS and the target FPS.
Example: when a subtitle file is converted from 24 FPS to 25 FPS, the factor is 24 / 25 = 0.96. A subtitle at 10:00,000 moves to 09:36,000. The whole subtitle track is compressed proportionally.
These values appear frequently in film, PAL, NTSC, streaming and editing workflows. Use the table as a guide when you are not sure which direction to choose.
| From FPS | To FPS | Factor | Typical use case |
|---|---|---|---|
| 23.976 | 24 | 0.9990x | Film or streaming footage has been conformed to true 24 FPS. |
| 24 | 25 | 0.9600x | Film subtitles need to match a PAL / European video version. |
| 25 | 24 | 1.0417x | PAL subtitles need to be moved back to a 24 FPS film version. |
| 29.97 | 30 | 0.9990x | NTSC-like sources are normalized to 30 FPS. |
| 30 | 29.97 | 1.0010x | 30 FPS subtitles need to match 29.97 FPS footage. |
Drift often looks small at the start, but it grows with every minute. That is exactly why FPS conversion is different from shifting all subtitles by a few milliseconds.
09:36,000 using the formula 600 seconds × 24 / 25. The difference is 24 seconds. This growing offset is what people call subtitle drift. If all subtitles are early or late by exactly the same amount throughout the video, you do not need FPS conversion. A constant offset is enough. If the error grows over time, the FPS Converter is the right tool.
| Problem | Best tool | Why |
|---|---|---|
| Subtitles are, for example, 2 seconds late everywhere. | Subtitle Time Shifter | The offset is constant and only needs to be added or subtracted. |
| Subtitles match at the beginning but are clearly off by the end. | Subtitle FPS Converter | The timeline must be stretched or compressed proportionally. |
The full conversion runs locally with JavaScript in your browser. Your SRT or VTT file is not uploaded to our servers. The tool reads the timestamps, calculates the FPS factor and writes a new file with adjusted start and end times.
The most common video frame rates are 23.976 for many streaming and NTSC-related film sources, 24 for cinema and film masters, 25 for PAL and Europe, and 29.97 or 30 for NTSC, broadcast and online workflows.
If your subtitles are not drifting but are consistently early or late across the whole video, FPS conversion is not necessary. Use the Subtitle Time Shifter to move every timestamp by a fixed value.
Go to Subtitle Time ShifterDrop your subtitle file (SRT or VTT) into the tool, or click to select it from your device.
Enter the FPS your subtitles were created for and the FPS of the target video.
Click “Convert frame rate”, check the preview and download the synchronized subtitle file.
It means scaling all subtitle timestamps proportionally so they match a video that has a different frame rate or running time.
When footage is conformed from one frame rate to another, the effective running time can change. Subtitle timings then have to be scaled by the same ratio.
The tool supports SubRip (.srt) and WebVTT (.vtt). VTT files keep the dot format for milliseconds, while SRT files use commas.
In VLC, open Tools > Media Information > Codec Details. You can also use MediaInfo, Premiere Pro, DaVinci Resolve or Final Cut Pro.
No. A time shift adds the same value everywhere. FPS conversion scales the entire timeline. For 24 → 25 FPS, each time value is multiplied by 0.96.
That is typical FPS drift. The error grows over time because the subtitle file and the video use different timelines.
Yes. Once the drift is fixed, use the Subtitle Time Shifter if the subtitles are still slightly early or late by a constant amount.