Video Speed Changer (Fast Forward & Slow Motion)
Choose a video and set a speed to make a fast-forward or slow-motion clip. Pick anything from 0.25x to 4x, and the video and audio are re-timed to match. It uses your browser’s built-in video encoder (WebCodecs), so the file is never uploaded. To change the format or trim a clip, use the Video & Audio Converter; to change the speed of audio alone, use the Audio Speed & Pitch Changer.
🔒 Runs in your browser · Your data is never sent to a server
You can also drag and drop a file here
Enter a multiplier from 0.25 to 4 (for example 2 for double speed, 0.5 for half speed).
Audio is played back at the new speed, so it sounds higher when sped up and lower when slowed down (pitch is not preserved).
Result
How to use
- Choose a video file (drag and drop also works).
- Enter a multiplier in "Playback speed", or pick one of the preset buttons.
- Pick the "Output format" and "Quality". If you do not need sound, check "Remove audio (video only)".
- Press "Convert", then save the result with "Download" when it finishes.
Notes
- Audio pitch is not preserved. It follows the playback speed, so voices sound higher when sped up and lower in slow motion. To change speed while keeping the pitch, extract the audio and use the audio speed and pitch tool instead.
- The video is re-encoded to change its speed, so some quality is lost. "High" keeps the loss small but makes a larger file.
- When speeding up, frames are dropped so the output stays at or below 60 fps. When slowing down, no frames are interpolated, so motion can look choppy.
- Speed depends on your device. Long or high-resolution videos can take a while or fail when memory runs out.
- Keep this tab open and in the foreground while converting. Some browsers slow down or pause background tabs.
- Available input and output formats vary by browser. MP4 (H.264) output works best in Chrome, Edge and Safari, WebM output in Chrome and Edge, and Firefox may have limited encoding support.
- The file size limit is 1 GB. The output is built in memory, so large files use a lot of RAM. Subtitles and extra audio tracks are not carried over.
- All processing happens in your browser; the file you choose is never sent to a server.
Glossary
Pitch
How high or low a sound is. Playing audio faster raises its pitch and playing it slower lowers it. This tool does not correct the pitch.
fps (frame rate)
The number of frames shown per second. Speeding a video up packs the frames closer together and raises the fps, so this tool drops frames to stay at 60 fps or below.
WebCodecs
A standard browser API for compressing and decompressing video and audio. This tool uses it to convert files inside your browser.
FAQ
What range of speeds can I set?
From 0.25x (quarter speed) to 4x. Enter "2" for double speed or "0.5" for half speed; the output length is the original length divided by the multiplier.
What happens to the audio pitch when I speed a video up?
The audio is re-timed along with the video, so its pitch is not preserved: it sounds higher when sped up and lower when slowed down. To keep the pitch, extract the audio and process it with the Audio Speed & Pitch Changer.
Why does my slow-motion video look choppy?
Slowing down stretches the gap between frames, and this tool does not interpolate new frames. Videos with a low original frame rate look more jerky in slow motion.
Can it handle long or large videos?
Files up to 1 GB are accepted. Because the video is re-encoded in your browser, long or high-resolution videos can take a while or run out of memory. Lowering "Resolution (max height)" makes it lighter.
Is my video uploaded to a server?
No. Conversion runs inside your browser using WebCodecs, and the file you choose is never sent anywhere.
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