Change Speed
Speed up or slow down videos and audio from 0.25× to 4×, keeping the voice pitch natural.
Free · No upload · 100% on your device
Change Speed
Choose video or audio files, or drop them here.
MP4, MOV, MKV, WebM, AVI and more · No size or length limit. Nothing is uploaded.
100% on your device
How to use Change Speed
- Choose your video or audio files, or drop them on the page.
- Pick the settings in the side panel.
- Select “Change speed”. The first use downloads the video engine once.
- Download the result. Your original file is left unchanged.
Private by design. Your files are processed in this browser tab and are never uploaded to KittySuite.
About Change Speed
Audio is time-stretched so voices keep their normal pitch, even at 2× or 0.5×. Very large changes (0.25× or 4×) are made in steps and sound more processed. Remove the audio for silent time-lapses. Audio files keep their format; videos are saved as MP4.
Processing happens in this tab with FFmpeg compiled to WebAssembly; your files are never uploaded. The first video or audio tool you use downloads the 10 MB engine once and keeps it cached for next time. Long or high-resolution videos take longer than on a desktop editor, especially on phones, where files are processed one at a time to stay within memory. Keep the tab open until the download appears.
Change Speed: frequently asked questions
How do I speed up a video?
Choose the file and a speed from 0.25× to 4×, then save. Audio files keep their format; videos are saved as MP4.
Will voices sound like chipmunks?
No. Audio is time-stretched so voices keep their normal pitch. Very large changes such as 0.25× or 4× sound more processed.
Can I make a silent time-lapse?
Yes. Choose a high speed and turn on “Remove audio”.
Does it work with audio files too?
Yes. You can speed up or slow down MP3, WAV and other audio files as well as videos.