Subtitle Framerate Converter
Rescale subtitle timings between frame rates to fix subtitles that slowly drift out of sync, the classic PAL/NTSC mismatch.
100% private. Your files are processed locally in your browser and never uploaded to a server.
Drop a subtitle file
or click to browse · SRT, VTT, ASS/SSA
What this tool does
A frame-rate converter multiplies every subtitle timestamp by
source FPS ÷ target FPS. When a film is converted between standards,
for example a 24 fps movie sped up to 25 fps for European PAL TV, the audio (and the
matching subtitles) play slightly faster, so subtitles made for one version drift against the other.
How to tell you need this (not the offset shifter)
- The subtitles line up at the start but get progressively more out of sync toward the end.
- The error grows steadily, a few seconds off by the finale.
That growing error is the signature of a frame-rate mismatch. A constant offset can't fix it; a proportional stretch can.
Common conversions
- 25 → 23.976 fps: subtitles from a PAL source for an NTSC/film release.
- 23.976 → 25 fps: subtitles from a film/NTSC source for a PAL release.
Frequently asked questions
Why do my subtitles slowly drift out of sync?
The video was most likely converted between frame rates, for example a 25 fps PAL version versus a 23.976 fps source. The audio plays at a slightly different speed, so subtitles made for one version drift against the other.
Which source and target framerate should I choose?
Set the source to the fps the subtitles were made for and the target to your video’s fps. The most common pair is 25 and 23.976 fps.
How is this different from shifting subtitle timing?
Framerate conversion proportionally stretches every timestamp, so later cues move more than early ones. Shifting moves all cues by the same constant amount.