Video Speed Changer
Speed up a long video, or slow down a moment into slow motion. The sound stays in sync and keeps its natural pitch, and everything happens on your device.
Drop a video file here or
Your video never leaves your device. Everything is processed in this browser tab: no upload, no server copy.
How to change the speed of a video
- Drop a video onto the box or click "Choose video".
- Pick a speed: below 1× slows the video down, above 1× speeds it up. Choose how the sound should behave.
- Click "Change speed", watch the preview, then click "Download video".
Speed up, slow down, and keep the sound right
Changing the speed of a video means changing when each frame is shown. At 2× every frame is shown for half as long, so a 10-minute tutorial plays in 5 minutes; at 0.5× each frame lasts twice as long for a slow-motion effect. Fast-forwarded videos are capped at 60 frames per second, which keeps files small and plays smoothly everywhere.
The sound is adjusted to match. By default it is time-stretched so voices keep their normal pitch, the same way video players speed up lectures and podcasts. Choose "Change speed and pitch" for the classic chipmunk effect when speeding up, or a deep, slow voice when slowing down.
Good to know
Slow motion works best on videos recorded at a high frame rate, such as 60 or 120 fps phone footage; slowing down 30 fps video makes motion less smooth because no new frames are invented. The result is an MP4 file encoded at high quality on your own device.
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Frequently asked questions
Is my video uploaded?
No. The video is processed by your own browser using its built-in video encoder. Nothing is sent to a server, so private videos stay private.
Will the sound stay in sync?
Yes. The sound is stretched or squeezed by exactly the same amount as the picture.
Does speeding up change voices?
Not by default: voices keep their normal pitch. Choose "Change speed and pitch" if you want the chipmunk effect.
How do I make a timelapse?
Choose 4× or a custom speed up to 8×. For very long recordings, trim the part you need first with the Video Trimmer.
Which browsers does it work in?
Recent Chrome, Edge and Opera on desktop and Android, Safari 26 on Mac and iPhone, and Firefox 130 or newer on desktop. These browsers include the WebCodecs video encoder the tool uses.