Video speed changer
Pick a speed from 0.25× to 4×, watch the preview change instantly, then download an MP4. Voices keep their natural pitch, and the video never leaves this browser tab.
- No upload: runs in your browser
- Free, no watermark
- Exports MP4 (H.264 + AAC)
Drop or choose a video
MP4, MOV, WebM, MKV. It stays on this device.
More options
A 60-second clip at 2× becomes 30.0 s.
How to change the speed of a video
- Choose a video or drop it on the player. The file is opened locally; nothing is sent to a server.
- Pick a speed. Tap a preset or drag the slider. The preview plays at that speed straight away, using your browser’s own player, so you can judge it before exporting.
- Choose the audio: keep the pitch natural, let it follow the speed, or drop the sound.
- Press “Change speed”, wait for the bar, and download the MP4. Under “More options” you can trim the clip, cap the resolution or use quick mode.
The preview is instant because the browser simply plays the original faster or slower. The export is real work: FFmpeg decodes every frame, re-times it and encodes a new file, which is why it takes longer than the preview.
Frame strip: 30 fps in, 30 fps out
Source frames
- 0
- 1
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Output frames (first 12)
- 0
- 2
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- 22
What happens to frames when you change speed
A video is a stack of still pictures with timestamps. Changing speed rewrites those timestamps (FFmpeg’s setpts filter), then brings the result back to a normal frame rate. Speeding up means some frames are skipped. Slowing down means the same picture has to fill more time: it is repeated, or with Blend frames switched on, neighbouring pictures are mixed together. Neither invents detail the camera never captured, which is why real slow motion starts with a high-frame-rate recording (see the slow motion maker).
Speeding up sound: two ways
Original: 3 cycles of a note
After 2× · same wave shape, fewer repeats
atempo filter) cuts the audio into short overlapping slices and overlaps them tighter or looser, so waves keep their length and only the timing changes. The demo tones are synthesised in your browser. Common speeds and what they are good for
| Speed | New length | Typical use |
|---|---|---|
| 0.25× | 4× longer | Dramatic slow motion; best from 120 fps footage |
| 0.5× | 2× longer | Slow-mo replays, dance breakdowns, studying technique |
| 0.75× | 1.33× longer | Following fast talkers or tutorials |
| 1.25× | 0.8× length | Tightening a talking-head clip without it sounding rushed |
| 1.5× | 0.67× length | Lectures and screen recordings |
| 2× | half as long | Recipes, crafts, walkthroughs, fitting a time limit |
| 4× | a quarter as long | Cleaning, drawing and build montages |
Honest limits
- Speed: the in-browser encoder uses one CPU thread. Expect exports to take roughly one to several times the clip’s length on a laptop, more on phones. Choosing 720p output or “Fastest export” helps.
- Memory: browsers cap how much memory a page can use. Multi-gigabyte files or long 4K clips can fail; trim them first under More options.
- Codecs: most H.264, HEVC, VP9 and AV1 files decode fine. Some camera formats (ProRes RAW, certain 10-bit HDR files) may not, and HDR footage is exported as standard 8-bit.
- Phones: iOS Safari in particular may reload a tab that uses too much memory. Keep phone clips short.
Other speed jobs have their own pages: speed up a video, slow a video down, reverse it, turn it into a timelapse or change its frame rate. The theory is in how video speed changes work.
Questions people ask
Is my video uploaded anywhere?
No. VidSpeed loads a WebAssembly build of FFmpeg into your browser tab and processes the file there. The video never leaves your device, which also means there is no file-size limit on our side, only your device’s memory.
What speeds can I use?
Anything from 0.25× (four times slower) to 4× (four times faster) in steps of 0.01. For bigger jumps, the timelapse tool goes up to 60×.
Will voices sound like chipmunks?
Not unless you want them to. “Keep the voice’s pitch” uses FFmpeg’s atempo filter, which changes timing but not pitch. “Tape style” lets pitch rise and fall with speed, like an old cassette.
How long does it take?
Re-encoding runs on one CPU core in the browser, so it is slower than desktop editors. As a rough guide, a 1-minute 1080p clip takes a few minutes on a recent laptop and longer on a phone. Quick mode skips re-encoding for MP4/MOV files and usually finishes in seconds.
Which formats work?
Most MP4, MOV, M4V, WebM and MKV files with H.264, H.265/HEVC, VP8, VP9 or AV1 video can be read. The output is always an MP4 with H.264 video and AAC audio, which plays almost everywhere.
Does it work on iPhone and Android?
Yes, in Safari and Chrome, but phones give a browser tab much less memory. Short clips (under about a minute) and 720p output are the safe choice. Your phone’s own apps can also change speed; see our iPhone and Android guide.
Is this the Video Speed Controller browser extension?
No. Extensions such as Video Speed Controller change how fast a video plays while you watch it on a website; nothing is saved. VidSpeed changes the speed of a video file and gives you a new MP4 you can post or send. To just watch faster in your own player, its playback-speed setting is enough.
Can I share a speed setting?
Yes. “Copy a link” under the tool copies a URL such as vidspeed.app/?speed=1.5 that opens with that speed already chosen.
Is there a watermark?
No watermark, no account, no limit on how many videos you process.