EditSafely

Change Video Speed

Speed up or slow down an MP4 with pitch-preserved audio, right in your browser. Runs entirely in your browser, so your data never leaves your device.

Video

Drop a video here, or click to browse

Up to 5 GB · never leaves your device

Output

Press Change speed and the result appears here.

Options

Your videos never leave this tab

Change Video Speed is JavaScript that your browser has already downloaded, and it does the whole job on your own machine. On a normal site, a 5 GB video means 5 GB uploaded, a wait in somebody's queue, and 480 MB downloaded again. Here it means 0 bytes up and 0 bytes down.

  • No upload
  • No file size limit
  • Works offline once loaded
  • Nothing stored or logged

How to use Change Video Speed

  1. 1. Upload the MP4 video and review the analysis. Drop or browse for the .mp4 file whose speed you want to change. Videos up to 5 GB work: the file is read in small chunks rather than loaded whole, and it never leaves your device. The tool instantly analyzes the video and shows its duration, resolution, frame rate, codec and whether it carries an audio track.
  2. 2. Pick a playback speed. Choose anything from 0.25x slow motion to a 4x timelapse. Speeds above 1x shorten the video, speeds below 1x stretch it. When the video has audio, the sound is re-timed with a pitch-preserving filter, so a 2x lecture still sounds like a normal voice instead of a chipmunk, and slowed audio keeps its natural tone.
  3. 3. Change the speed and download the video. Press Change speed to start. The tool re-encodes the video in your browser with a progress bar as it works, then shows the new duration next to the original. Preview the result and download the finished MP4, named with the speed you picked, like clip-2x.mp4.

When to use Change Video Speed

Change Video Speed re-times an MP4 to play faster or slower, entirely in your browser without uploading it to any server. The picture is re-encoded at the new speed and the audio is stretched or compressed without changing its pitch, so the result sounds natural at any setting.

  • Turning long footage into a timelapse. A slow screen recording, a drive, or an hour of cooking becomes a snappy overview at 4x; the file also gets much shorter, which makes it easier to share.
  • Slowing down action for analysis. Drop a golf swing, a goal, or a product demo to 0.25x or 0.5x to study every frame; the slowed audio keeps its pitch, so commentary stays intelligible.
  • Speeding up lectures and meetings. Recorded talks and meeting captures are comfortable to follow at 1.25x to 2x; the pitch-preserving audio keeps voices natural, so you save time without the chipmunk effect.
  • Fitting clips into social media limits. A clip that runs a few seconds over a platform's length limit fits after a subtle 1.25x speed-up, usually without viewers noticing anything changed.

Examples

Double the speed

Input

lecture.mp4 (40:00) + 2x

Output

lecture-2x.mp4 that plays in 20:00 with natural-sounding voice

Quarter-speed slow motion

Input

goal.mp4 + 0.25x slow motion

Output

goal-0.25x.mp4 stretched to four times its length

About the Change Video Speed tool

Change Video Speed runs as plain JavaScript in your browser tab, with no server behind it. Speed up or slow down an MP4 with pitch-preserved audio, right in your browser. Whatever you put in stays on your device from start to finish.

The tool is part of EditSafely's Video Tools section, 12 single-purpose utilities built around the same idea: open the page, get the result, keep your data to yourself.

You can shape the output with the Playback speed setting, and the result refreshes the moment you change it. The finished file is put together in browser memory and saved with the Download button, so it never touches a server on the way to your disk. 2 worked examples further down the page show exactly what the tool produces for real inputs.

That local-first design has practical benefits beyond privacy. The tool keeps working on a flaky connection once the page has loaded, results are instant because nothing round-trips to a server, and it is safe to use with confidential material.

Frequently asked questions

Is Change Video Speed free to use?

Yes, it is completely free. All 2,671 tools on EditSafely work without an account, a subscription or usage limits.

Are my files uploaded to a server?

Everything happens locally. Your browser downloads the tool's code once, then does all the processing itself; nothing you enter is transmitted, stored or logged. You can even go offline after the page loads and it will still work.

Which files does Change Video Speed accept?

It accepts MP4 videos. There is no file size cap imposed by a server; very large files are limited only by your device's memory.

Do I need to sign up or install anything?

No. The tool works in any modern browser on desktop, tablet or phone. There is no account to create, no extension to add and no software to install.

How do I save the output?

Click the Download button once the result is ready. The file is built in your browser's memory and handed straight to your downloads folder, without passing through a server.

Related tools

All Video Tools →

Trim MP4

Cut the start and end off an MP4 on a visual timeline, right in your browser.

Compress MP4

Shrink an MP4 video's file size right in your browser, no upload needed.

Mute a Video

Strip the audio track from an MP4 or MOV losslessly, right in your browser.

Convert MP4 to GIF

Turn a clip from an MP4 video into a looping GIF, right in your browser.