Skip to content
ClipTools
Edit

Video Speed Changer

Speed up or slow down any video with pitch-corrected audio

Share this tool

100% private. Your file is processed locally in your browser with WebAssembly — it is never uploaded to a server, stored, or seen by anyone.

Rate this tool

Used it? Tap a star — your rating helps others find tools that work.

No ratings yet — be the first to rate it.

The Video Speed Changer lets you speed up or slow down any video and adjusts both the picture and the audio in sync. Whether you want a 2x fast-forward of a tutorial or a 0.5x slow-motion replay, it re-times the footage and pitch-corrects the audio so voices stay natural instead of sounding chipmunky or droning. Pick a speed from a slow 0.25x up to a fast 4x and download a standard MP4.

Everything runs locally in your browser using ffmpeg compiled to WebAssembly (ffmpeg.wasm) — your video is never uploaded to any server. The tool re-times the video stream with ffmpeg's setpts filter and adjusts the audio tempo with the atempo filter, which changes duration without altering pitch. It is built for content creators, students, editors, and social media users who need a quick, private way to change video speed without installing software or creating an account.

Why use this tool

Pitch-corrected audio that stays natural

Unlike basic players that just play faster, this tool uses ffmpeg's atempo filter to change audio tempo without shifting pitch, so sped-up voices do not sound squeaky and slowed-down audio does not sound muddy.

Wide speed range from 0.25x to 4x

Create smooth slow-motion at 0.25x or 0.5x, gentle pacing tweaks at 1.5x, or fast-forward and time-lapse effects at 2x and 4x — all from one tool with audio kept perfectly in sync.

Completely private, nothing uploaded

Your video is re-timed locally with ffmpeg.wasm in your browser, so the file never touches a server. This keeps personal, confidential, and copyrighted footage on your own device.

No software or signup required

There is nothing to install and no account to create. The tool runs in any modern browser on desktop or mobile, outputs a standard MP4, and is free with no watermark.

How to use the Video Speed Changer

  1. Upload your video

    Drag and drop your video onto the upload zone or click to browse and select an MP4, MOV, AVI, MKV, or WebM file from your device.

  2. Choose a speed

    Pick a speed multiplier such as 0.25x or 0.5x to slow the video down, or 1.5x, 2x, or 4x to speed it up.

  3. Confirm pitch-corrected audio

    Leave audio enabled so the atempo filter keeps voices and music at a natural pitch, or mute the audio if you only want the re-timed picture.

  4. Process the video

    Click Change Speed and watch the progress bar as ffmpeg.wasm re-times the video locally in your browser without uploading anything.

  5. Download the result

    Download your sped-up or slowed-down video as a standard MP4 file ready to share or edit further.

Popular use cases

  • A YouTuber speeds up a long screen-recorded tutorial to 1.5x or 2x to keep viewers engaged while keeping the narration clear and natural-pitched.
  • A coach or athlete slows match footage to 0.25x or 0.5x to analyze technique frame by frame in detailed slow motion.
  • A social media creator turns a long clip into a punchy 4x fast-forward or time-lapse for TikTok, Instagram Reels, or Shorts.
  • A student or presenter slows down a fast-talking lecture or demo recording to 0.5x to transcribe or follow along more easily.

Frequently asked questions

Is the Video Speed Changer free to use?
Yes, the Video Speed Changer is completely free with no signup, watermark, or usage limits. You can speed up or slow down as many videos as you want at no cost because all processing happens on your own device rather than on paid servers.
Are my videos uploaded to a server?
No. Your video is processed entirely in your browser using ffmpeg.wasm (WebAssembly), so the file never leaves your device and is never uploaded to any server. This makes it private by design and safe for confidential or personal footage.
Does changing the speed keep the audio in sync and at the right pitch?
Yes. The tool re-times the video with ffmpeg's setpts filter and adjusts the audio with the atempo filter, which changes tempo without changing pitch. Voices and music stay natural-sounding instead of becoming high-pitched when sped up or deep when slowed down, and audio stays in sync with the picture.
What speed range can I choose?
You can slow a video down to 0.25x or speed it up to 4x, plus common presets like 0.5x, 1.5x, and 2x. For speeds above 2x, the tool automatically chains multiple atempo filters (for example atempo=2.0 plus a second pass), because a single atempo filter only supports a 0.5x to 2x range.
What video formats are supported?
You can upload MP4, MOV, AVI, MKV, WebM, FLV, WMV, and other common video formats. The output is always a standard MP4 file (H.264 video with AAC audio) that plays on phones, computers, and social platforms.
Will changing the speed reduce video quality?
Re-timing keeps the original resolution and frame content, so there is no rescaling. Because the output is re-encoded to MP4, there is minor compression typical of any H.264 export, but the visible quality stays very close to the source. Slowing a video down does not add new frames, so very slow speeds may look slightly less smooth than true slow-motion footage shot at a high frame rate.
How long does it take to change a video's speed?
Most short clips finish in well under a minute. Processing time depends on your device's CPU, the video's length and resolution, and the selected speed, since the file is encoded locally in your browser rather than on a remote server.
Can I create a slow-motion or time-lapse effect with this tool?
Yes. Choose a speed below 1x (such as 0.5x or 0.25x) for a slow-motion look, or a speed above 1x (such as 2x or 4x) for a fast-forward or time-lapse effect. Both adjust the audio tempo to match, and you can remove the audio first if you want a silent time-lapse. The practical file size is around 1 GB, limited mainly by your device's available memory.

Related tools

Video Trimmer & Cutter

Cut a video to any start and end time with zero quality loss

Online Video Compressor

Shrink video file size in your browser, no upload required

Remove Audio from Video

Mute any video and keep full quality — free, in your browser