Free tool · runs in your browser

Video Speed Changer

Speed up tutorials, slow down sports replays, or hit a tight runtime by re-timing any video from 0.25× to 4×. Keep the audio in its original pitch, or allow it to shift for a deliberate chipmunk / slow-mo effect — FFmpeg runs locally in your browser.

How to use this tool

  1. 01

    Upload your video

    Any format FFmpeg supports — it stays in your browser.

  2. 02

    Set the speed

    0.5 for half speed, 2.0 for double speed, anywhere from 0.25× to 4×.

  3. 03

    Choose pitch handling

    Preserve pitch for speech and music; shift for chipmunk / slow-mo special effects.

  4. 04

    Render and download

    Output duration = original duration ÷ speed; the new length is shown before you render.

Why this matters

Most editors expose 0.5× and 2× as buttons and make anything in between a timeline-nudging chore, and quick online converters either skip audio handling entirely or chipmunk every voice. Re-timing should be one number plus a single decision about what happens to the audio.

This does exactly that, locally: a precise multiplier, an explicit pitch-preserve vs pitch-shift choice, and the resulting duration shown before you commit. To re-time only part of a clip, trim the section first with the Video Trimmer and then change its speed here.

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FAQ

FFmpeg's atempo filter only accepts a rate between 0.5 and 2.0 in a single pass, because changing tempo further in one step degrades audio quality and stability. To reach 0.25× or 4× this tool chains several atempo filters (e.g. two 2.0× passes for 4×), each staying inside the supported range so the result stays clean.

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