Change the speed of a video
From 0.25× to 4×. Audio stays in sync and keeps a natural pitch (no chipmunk voices).
Your files never leave your device
How to change the speed
- 1
Upload the video
Any common format.
- 2
Pick the speed
0.25×, 0.5×, 0.75×, 1.25×, 1.5×, 2× or 4×.
- 3
Download the MP4
With audio in sync.
Why use this tool
Natural pitch
Audio changes speed without going squeaky or deep — no chipmunk voices.
Guaranteed sync
Video and audio are processed together: they never drift.
Wide range
From 0.25× slow motion to 4× time-lapse.
Private
The video never leaves your device: ffmpeg runs in your browser.
Frequently asked questions
Does the audio get distorted?
We use tempo correction (atempo): the speed changes but the pitch stays natural across the whole range.
Does slow motion invent frames?
No: at 0.25× each frame just lasts longer. No AI frame interpolation — we're upfront about that.
Does the duration change?
Yes: at 2× it's half as long; at 0.5× twice as long. File size scales accordingly.
What if my video has no audio?
That's detected automatically and only the video is processed — no errors.