Change Video Speed

How to speed up or slow down a video

Drop the video above and drag the Playback speed slider. It runs from 25% to 400% of normal speed, so 0.25× to 4×. Press Convert and download the MP4. A 2× video is half as long, and a 0.5× video is twice as long.

Audio stays in sync at a natural pitch

The picture is retimed with FFmpeg's setpts filter and the sound with its atempo filter, chained where needed for speeds beyond 2× or below 0.5×. The audio speeds up or slows down with the picture but keeps its pitch, so voices don't sound like chipmunks or slurred. Videos without sound are retimed the same way.

Slow motion limits

Slowing a video repeats frames rather than inventing new ones. A 30 fps clip at 0.5× plays like 15 fps footage and can look choppy. Clips recorded in your phone's slow-motion mode at 120 or 240 fps slow down far more smoothly. The result is encoded as H.264 with AAC audio.

Processed on your device

Change video speed from 0.25× to 4× and keep the audio in sync with the picture, at a natural pitch. A media engine inside your browser does the work, so the video never leaves your device.

Works in your browser

Video encoding runs in this browser tab, on your own device. There is no upload and no queue. Your device does all the work, so a large or long clip can take a minute or more.

Before you start

Input: MP4, MOV, MKV, WEBM, AVI, and M4V. Output: MP4. The settings appear before anything runs, so you can check them first. Your original file is never changed.

Video work uses a lot of memory and CPU. Try a short clip first and check that the sound and playback work. On a phone, split large batches into smaller ones.

Keep the original until you have opened and checked the result. The work happens in this browser tab, so the size you can handle depends on your device's memory, your browser and the file itself.

How to change Video Speed

1. Add the source video above.
2. Choose the options for the result.
3. Press Convert and download the MP4.