⏩ Video Speed Changer
Speed up or slow down any video from 0.01× to 10000× — with audio that keeps its natural pitch, no chipmunk voices. Preview and download, all in your browser. Free, private & no watermark.
Make a clip faster (time-lapse feel) or slower (slow motion) — audio is time-stretched so voices don't turn into chipmunks. All in your browser.
Speed Up or Slow Down — Privately
Smooth speed control with natural-sounding audio and clean output, without a single frame leaving your browser.
0.01× to 10000×
Speed up for a time-lapse feel or slow down for slow motion — use presets, the log slider, or type an exact value.
Natural-Pitch Audio
Audio is time-stretched, not just played faster — so voices and music keep their real pitch, no chipmunk effect.
Or Go Silent
Prefer no sound? Remove the audio in one click for a clean, silent sped-up or slowed clip.
Live New Length
See exactly how long the result will be before you process — the duration updates as you change the speed.
No Upload, No Watermark
Powered by in-browser ffmpeg — your video stays on your device and the result is clean.
Works Everywhere
Responsive down to 280px with full dark mode; runs offline after the one-time engine load.
How to Change Video Speed
Four steps — the result re-encodes in real time.
Add a video
Drag and drop or tap to choose an MP4, WebM or MOV file.
Choose a speed
Tap a preset, drag the slider, or type an exact value (0.01×–10000×) — above 1× speeds up, below 1× slows down.
Keep or drop audio
Leave 'Keep audio' on for natural-pitch sound, or uncheck it for silent output.
Apply & download
Preview the re-timed clip and download it — no upload, no watermark.
Frequently Asked Questions
How to change speed, the chipmunk-audio fix, why slow-mo can judder, privacy, range, quality and uses.
How do I speed up or slow down a video?
Drop your video in, then drag the speed slider or tap a preset — 2× and 4× to speed up, 0.5× or 0.25× for slow motion. The new length is shown instantly. Hit Change speed and the re-timed video appears to preview and download. Everything runs in your browser; nothing is uploaded.
Will the audio sound like chipmunks when I speed it up?
No. Many basic tools just play the audio faster, which raises the pitch into chipmunk territory. This tool time-stretches the audio properly, so a 2× clip plays twice as fast but voices and music keep their natural pitch. You can also remove the audio entirely if you prefer a silent result.
Why does slowing a video down sometimes look juddery?
Slow motion only looks smooth if there are enough frames to stretch. A normal 30 fps video slowed to 0.25× has to hold each frame four times as long, which can look stuttery, because the extra in-between moments were never captured. True buttery slow motion comes from filming at a high frame rate in the first place; software can only stretch the frames it's given.
Is my video uploaded anywhere?
No. The speed change runs entirely on your device using ffmpeg compiled to WebAssembly — your video never leaves your browser, there's no watermark, and nothing is stored. It works offline once the engine has loaded.
What speed range can I use?
Anywhere from 0.01× (one-hundredth speed) up to 10000× (extreme time-lapse). Use the presets, drag the slider, or type an exact number like 1.35 or 250 into the 'Exact speed' box. The slider is logarithmic, so the everyday 0.5×–2× range still gets plenty of room despite the huge span. Bear in mind the extremes are exactly that: at 0.01× a 10-second clip becomes nearly 17 minutes and looks very juddery (there aren't enough frames to fill the time), and at very high speeds almost every frame is discarded, so a short clip can collapse to a fraction of a second — both are real effects, not bugs. Extreme fast speeds only produce meaningful output from long source videos.
Does changing the speed reduce quality?
Changing speed requires re-encoding the video, which involves a small, usually invisible quality change — the same as any video edit that isn't a pure copy. The tool uses a high-quality encoder setting, so for normal footage you won't notice a difference.
Why is there a one-time download?
The tool uses ffmpeg — the engine behind most video software — compiled to run in your browser. It's about 30 MB and is fetched once on first use, then cached, so later changes start instantly. It's what lets everything run privately, with no server.
What can I use this for?
Speeding up is great for tutorials, time-lapses, condensing long clips and that energetic 'fast-forward' look; slowing down is perfect for emphasising a moment, analysing a technique, or a dramatic slow-motion effect. Pair it with the Trimmer to grab just the part you want first.