Subtitle Frame Rate Converter
Fast. Private. Perfect.
Scale subtitle timecodes between video frame rates. Fix the 4% NTSC/PAL speedup, match 24fps cinema subtitles to 25fps video, and more.
Drag & drop your subtitle file here
or click to browse
SRT, VTT, ASS, SSA, LRC, SBV, TTML, SCC, STL, SMI, TXT
How It Works
Select your subtitle file.
Pick the original video frame rate the subtitles were timed for.
Pick the target frame rate of the video you want to play them with.
Choose the output format (SRT, VTT, or ASS).
Click Convert and download the rescaled subtitle file.
Why Choose AllSubConverter?
Your Privacy Matters
Everything runs in your browser. Your files are never uploaded.
Lightning Fast
Optimized processing engine converts files in seconds.
Truly Unlimited
No file size limits. No daily limits. Completely free.
Works Everywhere
Works on Windows, Mac, Linux, iOS, Android - any modern browser.
Key Features
Common Use Cases
NTSC to PAL Conversion
Film is captured at 23.976 fps but European PAL releases play at 25 fps, a 4.04% speedup. Scaling timecodes by 25/23.976 fixes the drift.
Cinema to TV
Movie subtitles authored at 24 fps need a 25/24 ratio to stay in sync on a 25 fps broadcast master.
Broadcast Captioning
Move captions between 29.97 and 30 fps deliverables for North American broadcast without re-timing each cue by hand.
High Frame Rate Video
Convert standard 24/25 fps subtitles to 48/50/60 fps HFR masters while keeping every cue aligned.
Interlaced to Progressive
Repurpose 59.94/60 fps interlaced captions for 29.97/30 fps progressive web delivery.
Frequently Asked Questions
It multiplies every cue start and end time by the ratio targetFps / sourceFps. For 23.976 to 25 that ratio is about 1.0427, which shortens each cue by roughly 4% and exactly cancels the NTSC-to-PAL speedup.
Sync adds a fixed offset or a two-point linear shift. Frame rate conversion multiplies the timecodes, so the correction grows with time. That is exactly what a frame-rate mismatch needs.
Input: SRT, VTT, ASS, SSA, LRC, SBV, TTML, SCC, STL, SMI. Output: SRT, VTT, or ASS.
The speed adjuster scales timing by an arbitrary playback-speed factor you choose (for example 1.25x). The frame rate converter instead computes the ratio from two named frame rates, so you get the exact mathematical correction for a frame-rate mismatch.
Gradual drift that gets worse toward the end of the video is the classic symptom of a frame-rate mismatch. Converting from the source to the target frame rate removes the drift across the whole file.
Yes. Everything runs client-side. No subtitle data is ever sent to a server.