Is my video uploaded anywhere?

No. ffmpeg.wasm runs entirely inside your browser. The file is processed locally and never leaves your device.

Does it work on mobile?

Yes. Works on iPhone Safari and Android Chrome without installing any app.

Will resizing change the aspect ratio?

Not when "Keep aspect ratio" is checked — the height is computed automatically so the picture is never stretched.

Does resizing reduce file size?

Yes, dramatically. Halving the resolution removes 75% of pixels per frame, so a 1080p → 720p resize typically produces a file roughly 50% smaller at comparable quality.

Is the audio re-encoded too?

No. Audio is stream-copied with no re-encoding, so audio quality is identical to the source.

Video Resizer

Rescale a video to exact width and height — 1080p, 720p, 480p, or a custom size.

100% client-side · no upload

Video file (MP4, WebM, MOV…)

Settings Custom width (px) — used when preset is Custom Resolution preset Keep aspect ratio (auto-compute height)

Load a file to begin.

How to use

Choose your video file. MP4 and WebM are best supported.
Select a resolution preset (720p is a good balance of quality and size) or choose Custom and enter a width.
Keep "Keep aspect ratio" checked to avoid stretching. Click Resize video and download the result.

Related tools

More ways to use this tool

Frequently Asked Questions

Is my video uploaded anywhere?: No. ffmpeg.wasm runs entirely inside your browser. The file is processed locally and never leaves your device.
Does it work on mobile?: Yes. Works on iPhone Safari and Android Chrome without installing any app.
Will resizing change the aspect ratio?: Not when "Keep aspect ratio" is checked — the height is computed automatically so the picture is never stretched.
Does resizing reduce file size?: Yes, dramatically. Halving the resolution removes 75% of pixels per frame, so a 1080p → 720p resize typically produces a file roughly 50% smaller at comparable quality.
Is the audio re-encoded too?: No. Audio is stream-copied with no re-encoding, so audio quality is identical to the source.

Last updated: 2026-05-20 By jarvisbox