Change Video Speed Online — Speed Up or Slow Down MP4 Clips

Speed a video up or slow it down from quarter speed to four times, re-timing the picture and its audio together.

Making a recording play faster or slower changes how long it lasts, and doing that properly means re-timing the picture and the soundtrack by the same factor so they never drift apart. Choose a multiplier between a quarter speed and four times, see the new running time before you commit, and export a re-timed file.

How to speed up or slow down a video

  1. Drop an MP4, MOV or M4V clip onto the page; the source preview plays it as recorded.
  2. Choose a multiplier from the Speed list: 0.25×, 0.5×, 0.75×, 1.25×, 1.5×, 2× or 4×.
  3. Compare the new duration printed under the list with the original running time.
  4. Click Export MP4 and download the respeed-<your clip>.mp4 file when the progress reaches 100%.

Which playback speed to pick for your clip

Both tracks are re-timed by the same factor

Every frame's presentation timestamp is divided by the multiplier you choose, which is what compresses or stretches the timeline. The soundtrack is rendered through an offline audio graph at a matching playback rate, so a ten-minute recording at double speed produces five minutes of picture and five minutes of sound.

Doing only one of the two is the classic failure mode: the video finishes while the audio keeps going, or lips stop matching words a minute in. Driving both from a single multiplier makes that impossible by construction.

Pitch follows speed, deliberately

Playing audio faster raises its pitch, exactly as a tape or record does when spun quicker. That is what this tool does, and it is what almost every consumer speed control does, because the alternative — preserving pitch while changing duration — needs time-stretching that introduces its own smearing artefacts on music and room tone.

For a screen recording or a demonstration walkthrough, the raised pitch at 1.25× or 1.5× is barely noticeable and the tighter pacing is the whole point. At 4× speech becomes unintelligible, which is fine when the goal is a visual summary rather than a narration.

Reading the new duration before exporting

The panel prints the resulting running time next to the original so you can match a target length without arithmetic. If a slot allows three minutes and your capture runs five and a half, 2× overshoots in the useful direction and 1.5× lands closer.

Encoding happens at a frame rate scaled to match, so a slowed clip does not simply repeat frames and a sped-up one does not stutter. The quota is measured against the source length rather than the shortened output.

Speed change formats, output and free limit

Speed is changed on your own device

Frame timestamps and the audio render are both recalculated inside this browser tab. There is no upload step and no server queue to wait in: the file you pick is read locally, and the MP4 you download is written locally.

Questions people ask about Video Speed Changer

Will slowing footage down give me real slow motion?
It gives you longer playback of the frames you have, not extra ones. Genuinely smooth slow motion requires a camera that captured at a high frame rate to begin with; stretching standard footage will look progressively more stuttery the further you slow it.
Can I keep the voices sounding normal while speeding up?
Not on this page — pitch is tied to speed here. Preserving pitch requires a time-stretching algorithm whose artefacts on music and background noise are worse than the pitch shift itself at the modest multipliers most edits use.
Which multiplier should I pick to hit a specific length?
Divide the current running time by the length you want, then choose the nearest offered value and check the printed result. The available steps are quarter, half, three-quarter, one-and-a-quarter, one-and-a-half, double and quadruple.
Does a clip with no sound still work?
Yes. When there is no decodable audio the picture is simply re-timed on its own and a valid video-only file comes out, rather than the export failing because it could not find a track to process.
Can I change the speed of just one part of a video?
No, the chosen multiplier covers the entire clip. To speed up a single passage, cut that section out with the Video Trimmer, change its speed here, then join the pieces in an editor that handles several clips on one timeline.
Can I mute the audio while changing speed?
Not on this page, because the soundtrack is always re-timed along with the picture. Export the re-timed file, then load it into the Video Volume Changer and tick Mute there to produce a copy with a silent track.
What video formats can I speed up or slow down?
MP4, MOV and M4V files, which covers what phones and most cameras record. WebM, AVI and MKV cannot be read by this page's MP4 demuxer, and every export is saved as an H.264 MP4 regardless of the source container.
Do I need to sign up, and is there a watermark?
Neither. You can load and export without creating an account, and the MP4 carries no watermark or logo. The free tier only limits source length to 15 minutes per export, and a Pro license removes that cap.
Can I change video speed on my phone?
That comes down to your mobile browser: export needs the WebCodecs video encoder, and the page shows a red warning with export disabled when it is absent. We have not tested particular phones or tablets, so load a short clip first to see whether yours qualifies.

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Content reviewed 2026-09-27.