Subtitle Speed Adjuster
Fast. Private. Perfect.
Stretch or compress subtitle timing by a speed factor. Match subtitles to videos played at different speeds.
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.
Choose the speed factor using the slider or preset buttons. Values below 1.0 stretch timing (slower), values above 1.0 compress it (faster).
Select the anchor point: keep the first cue's start time fixed, or the last cue's end time fixed.
Choose the output format (SRT, VTT, or ASS).
Click Adjust and download the modified 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
Video Speed Change
You sped up or slowed down a video and need the subtitles to match the new playback speed.
Frame Rate Conversion
Adjust subtitle timing when a video was converted between frame rates (e.g., 24fps to 25fps causes a 4% speed difference).
PAL/NTSC Speedup
European PAL releases run 4% faster than film. Stretch subtitles to compensate.
Audiobook Sync
Adjust subtitle timing to match audiobook playback speed for language learning.
Gradual Drift Fix
When subtitles gradually drift out of sync, a speed adjustment can realign them across the entire file.
Frequently Asked Questions
The speed factor multiplies the duration of all cues. A factor of 1.5x compresses timing (subtitles appear faster), while 0.75x stretches it (subtitles appear slower). The anchor point stays fixed.
Subtitle sync shifts all cues by a fixed offset or applies a two-point linear correction. Speed adjustment scales all timing by a multiplicative factor, which is useful when the video itself was sped up or slowed down.
Yes, completely free with no registration, no watermarks, and no file uploads.
Start anchor keeps the first cue's start time unchanged and adjusts all other cues relative to it. End anchor keeps the last cue's end time fixed. Use start anchor when subtitles should begin at the same time, and end anchor when they should end at the same time.
Input: SRT, VTT, ASS, SSA, LRC, SBV. Output: SRT, VTT, or ASS.
Yes. Everything runs client-side. No subtitle data is ever sent to a server.