Does changing the speed keep the audio pitch?

Yes. Sondra uses a tempo filter that changes the speed while keeping the pitch natural, so voices and music still sound right.

Is my video uploaded to a server?

Never. Everything runs locally in your browser. Your file never leaves your device.

How slow or fast can I go?

You can choose from 0.25x (four times slower) up to 4x (four times faster), including 0.5x, 0.75x, 1.5x and 2x.

Will slow motion look smooth?

Slowing down stretches the existing frames, so the motion is smooth but not interpolated. For the smoothest result, start from a clip recorded at a high frame rate.

Which video formats are supported?

You can change the speed of MP4, MOV, MKV, WEBM and AVI files.

Yes. Changing video speed on Sondra is free, with no signup and no watermark.

Can I change video speed on my phone?

Yes. Sondra works in mobile browsers, with files up to 100MB on mobile and 500MB on desktop.

Does it work on a video without sound?

Yes. If the clip has no audio, only the video timing is changed and the result stays silent.

Does it work without internet?

After the page has loaded once, the speed change runs offline in your browser. You only need a connection to open the page the first time.

Change Video Speed - Slow Motion and Speed Up

Slow a clip down for smooth slow motion or speed it up to save time. Free, private, and right in your browser.

Drop a video here or click to upload

MP4, MOV, MKV, WEBM, AVI

Up to 500MB on desktop, 100MB on mobile

Fast 100% private Free

How to change video speed

Add your video

Drop in or pick the clip you want to slow down or speed up. It stays on your device.

Pick a speed

Choose from 0.25x up to 4x. Below 1x is slow motion, above 1x speeds it up.

Download

Save your new video at the speed you chose.

Why change video speed?

Slowing a video down turns fast action into smooth slow motion, perfect for sports, dance, a golf swing, or catching a detail the eye misses at full speed. Speeding a video up turns a long recording into a quick, watchable clip.

Sondra keeps the audio pitch natural while it changes the speed, so sped-up voices do not sound like chipmunks and slowed-down audio does not turn into a low rumble. You get a clean result at any speed from 0.25x to 4x.

It works with MP4, MOV, MKV, WEBM and AVI, adds no watermark, and runs entirely in your browser. Open the page, drop in your clip, choose a speed, and download.

What you can do with a speed change

Changing the playback speed is useful in a lot of situations. Here are the most common ones.

Slow motion replays

Slow down sports, stunts or a pet's antics to study or enjoy every frame.

Speed up tutorials

Make a long how-to or unboxing shorter and easier to watch.

Hyperlapse and timelapse

Speed up scenery, traffic or a build to a few quick seconds.

Fit a time limit

Speed a clip up slightly so it fits the length limit on Reels or Shorts.

Speed up video for any platform

A speed-changed MP4 plays everywhere. A few notes for the most popular places people share.

Instagram and TikTok

Speed up or slow down a clip to match a trend or fit the length limit.

YouTube

Speed up slow sections so viewers stay engaged, or add slow-motion highlights.

iPhone and Android

The new file plays in any gallery or messaging app, with no extra app needed.

Sports and fitness

Slow down a swing, lift or technique to review your form frame by frame.

Private by design

Most online speed changers upload your video to a server before processing it. Sondra does not. All the work happens inside your browser on your own device, so your video is never sent anywhere and nobody else can see it.

That also means there is no waiting for a long upload, no account to create, and no limit on how many videos you change. Close the tab and nothing is left behind.