--- title: "Subtitle FPS Converter" description: "Rescale every subtitle timestamp from one frame rate to another, such as 23.976 to 25, to fix captions that drift further out of sync the longer a video plays. Drop SRT or VTT files and download them retimed. Nothing is uploaded." url: https://findutils.com/media/subtitle-fps-converter/ category: media --- # Subtitle FPS Converter Rescale every subtitle timestamp from one frame rate to another, such as 23.976 to 25, to fix captions that drift further out of sync the longer a video plays. Drop SRT or VTT files and download them retimed. Nothing is uploaded. **Use this tool:** [Subtitle FPS Converter](https://findutils.com/media/subtitle-fps-converter/) ## Programmatic access - REST id `subtitle-fps-convert`: POST https://api.findutils.com/api/tools/subtitle-fps-convert/execute (reference: https://findutils.com/api/subtitle-fps-convert/) - MCP tool `subtitle_fps_convert` on https://mcp.findutils.com (reference: https://findutils.com/mcp/subtitle-fps-convert/) ## Why do subtitles drift? When a video is converted between frame rates — film at 23.976 frames per second broadcast at PAL's 25, say — every frame is played at a slightly different moment, and a subtitle file timed for the original runs at the wrong speed against the new copy. The error is not constant: it grows with elapsed time. A track that looks perfect in the opening minute can be a second out by the tenth and well over two minutes out by the end of a feature. Because the error grows, delaying the whole file by a fixed amount cannot fix it. Multiplying every timestamp by the ratio between the two frame rates can, and that is what this page does. ## Frequently asked questions ### How do I know frame rate is my problem? Check the first subtitle and the last. If the first is roughly right and the last is badly out, the error is growing with time and frame rate is the cause. If both are out by the same amount, it is a constant offset and the Subtitle Shifter is the tool you want. ### Which direction do I need? Source is the frame rate the subtitles were timed for; Target is the frame rate of the video you are watching. If the subtitles run ahead of the speech and the gap grows, your source rate is lower than your target. Swapping the two and re-running takes a second if you guess wrong. ### What is the factor shown under the rates? Source divided by target — the number every timestamp is multiplied by. 23.976 to 25 gives 0.95904, so the track becomes about 4% shorter. Seeing it before you convert is a quick check that you picked the pair you meant. ### Are my files uploaded? No. They are read in your browser with the File API and rescaled in the tab. Nothing is sent to a server, and you can confirm that in your browser's network tab. ### Can I use a frame rate that is not in the list? Yes. Choose Custom on either dropdown and type the rate. Anything between 1 and 1000 is accepted. ### Does it handle both SRT and VTT? Yes, and the output keeps whichever format came in. WebVTT cue settings such as line and align positions are preserved. ### Will this fix subtitles that are just a few seconds late? No, and it would make them worse. A constant offset needs a constant correction, which is what the Subtitle Shifter applies. This tool changes the speed of the track, not its starting point. ### What does the drift number next to each file mean? How far that file's last cue moved. It is the largest change in the file, so it is a good sanity check: a drift of a couple of minutes across a feature is normal for 23.976 to 25, while a drift of a few milliseconds means the two rates you picked are almost identical. ### Can I convert a whole season at once? Yes. Drop every file together; they are all rescaled with the same factor and download as a single ZIP. ### Does it change my subtitle text? No. Only timestamps change. Cue text, line breaks and cue settings are copied exactly as read. ## Related Tools - [Subtitle Shifter](https://findutils.com/media/subtitle-shifter/) - [Subtitle Merger](https://findutils.com/media/subtitle-merger/) - [SRT to VTT](https://findutils.com/convert/srt-to-vtt/) - [ASS to SRT](https://findutils.com/convert/ass-to-srt/) - [SBV to SRT](https://findutils.com/convert/sbv-to-srt/) - [Subtitle Extractor](https://findutils.com/media/subtitle-extractor/)