ALTools

ALTools

Change Video Speed

Speed up or slow down video for timelapse, slow motion, or tighter pacing. Adjust playback from 0.25× to 4× and export MP4 locally in your browser.

How to use this tool — step-by-step guide

How Video Speed Change Works

Upload MP4, MOV, WebM, or other common formats. Pick a speed preset from 0.25× to 4×, then export a new MP4. ALTools processes everything locally — no upload and no account.

Slow presets (0.25×–0.75×) stretch action for sports highlights, tutorials, or dramatic emphasis. Faster presets shorten long screen recordings or create a simple timelapse look on short clips.

When your clip has audio, it is stretched or compressed to match the new speed. Turn on Preserve pitch if you want voices and music to stay at a natural tone while playback gets faster or slower (files under 1 GB).

Speed changes re-encode video to H.264 MP4 for broad compatibility.

Longer clips take more time because every frame is decoded and re-encoded. Very large exports can stream directly to the save location you choose.

Download the new MP4 or combine with Trim Video and Compress Video before publishing.

Related Tools

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Combine an external audio track with your video. Replace or mix original audio — fast, private processing in your browser.
Merge Videos
Merge multiple videos (including TS segments) into one MP4 in the order you select.

Frequently Asked Questions

Will changing speed re-encode my video?

Yes. Speed changes adjust timing frame by frame, so the tool exports a new H.264 MP4. Quality follows your source; very long or high-resolution clips take longer to process.

What speed range is supported?

You can export between 0.25× (slow motion) and 4× (timelapse-style) using preset steps.

Does audio change with speed?

By default, audio speeds up or slows down with the picture — pitch rises when faster and drops when slower, similar to a simple speed effect in desktop editors. Turn on Preserve pitch to keep voices and music at a natural tone (available for files under 1 GB).

Do large files download differently?

On capable devices, exports above about 300 MB to 1 GB (depending on available memory) may ask you to pick a save location and stream the result straight to disk, so the finished file does not have to sit entirely in memory.

How is this different from reversing a video?

Speed change keeps frame order but plays faster or slower. Reverse Video plays from end to start.

Is my video uploaded?

No. Speed changes are processed locally in your browser.