No upload · No size limit · No watermark · No signup
Change video speed online — free, private, no upload
Speed footage up into a timelapse, or slow it down for dramatic effect. Everything runs locally in your browser — pick a preset or dial in a custom speed from 0.25x to 4x, watch the output length update, then download. The output is silent, since accurate speed-shifted audio isn't supported yet.
How it works
- Drop a video file. It stays on your device the whole time.
- Pick a speed preset — 0.5x, 1x, 1.5x or 2x — or drag the custom slider for anything from 0.25x to 4x. The output length readout updates live.
- Press change speed and watch the progress bar.
- Preview the result and download it — a silent, retimed MP4.
Frequently asked questions
Does the sped-up or slowed-down video keep its audio?
No, the output is silent. Correctly speed-shifting audio needs pitch-corrected time-stretching, which this tool doesn't implement yet, so rather than ship audio that sounds subtly wrong it honestly drops the audio track. It's ideal for timelapses, speed ramps and other clips you didn't need sound on anyway.
Is my video uploaded to a server?
No. Decoding, retiming and re-encoding all happen inside your browser using WebCodecs and mediabunny — the video file never leaves your device.
What speed range can I use?
Anywhere from 0.25x (quarter speed, for slow motion) up to 4x (for timelapses). Use one of the preset buttons for common speeds, or drag the custom slider for anything in between.
Is this good for making a timelapse?
Yes — that's the main use case. Speeding footage up to 2x-4x and dropping the audio is exactly what a timelapse needs, and the output duration readout shows you how short the result will be before you commit to processing it.
Does slow motion interpolate new frames, or will it look choppy?
It doesn't interpolate. Slowing a video down stretches each existing frame's on-screen time rather than generating new in-between frames, so very slow speeds on a low-frame-rate source can look choppy rather than buttery smooth.
What formats does it accept, and what do I get back?
Drop an MP4, MOV, WebM or MKV file. The output is always a silent H.264 video inside an MP4 container, the most widely compatible combination.