Video Resizer (Change Resolution)
Scale a video down to 1080p, 720p, 480p and more locally in your browser, keeping the aspect ratio.
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A video resizer changes the resolution (the pixel dimensions) of a video, for example scaling a 4K recording down to 1080p or 720p. Lowering the resolution shrinks the file substantially and makes a clip suitable for the web, email, or a target where full resolution is wasted, such as a small embedded player or a phone screen. Resolution is one of the biggest drivers of video file size: a 4K frame has four times as many pixels as 1080p, so reducing it has a dramatic effect on both size and the processing required to play it.
Frequently asked questions
Is my video uploaded to a server?
Does it keep the aspect ratio?
Can I upscale a video to a higher resolution?
How much smaller will the file be?
What format does it output?
What is the difference between resizing and compressing?
Is there a file size limit?
Does it work offline?
About Video Resizer (Change Resolution)
This tool resizes video entirely inside your browser using a WebAssembly build of FFmpeg. Your file is read locally, scaled to the resolution you pick, re-encoded as MP4 (H.264), and returned as a download, with nothing uploaded. It keeps the original aspect ratio automatically: you choose the target height (1080p, 720p, 480p, and so on) and the width is calculated to match, so the picture is never stretched or squashed.
Resizing always scales down, never up. Enlarging a low-resolution video to a higher one cannot add detail that was never captured; it just produces a bigger, blurrier file. Scaling down, on the other hand, is genuinely useful: it reduces file size, lowers the bandwidth needed to stream the clip, and can make an unwieldy recording practical to share. Because it re-encodes, resizing also re-compresses the video, often shrinking the file even more than the pixel reduction alone would suggest.
As with the other video tools, resizing runs single-threaded to stay compatible with the rest of the site and to keep everything private and local. Short and medium clips resize quickly; very large or long files take longer and use more memory.
Why 1080p and 720p are the numbers everyone knows
The familiar resolution labels, 1080p, 720p, 480p, all refer to the number of horizontal lines (the height in pixels) rather than the width. The p stands for progressive, meaning every line is drawn in order each frame, as opposed to the older interlaced i formats that drew alternate lines and could shimmer on motion. So 1080p is 1920 by 1080 pixels drawn progressively, and the height became the headline number because the widescreen 16:9 width follows automatically from it.
These specific heights are not arbitrary; they come from the HD broadcast and Blu-ray standards set in the late 1990s and 2000s, which the whole industry then standardised around. Because cameras, screens, streaming services and codecs all settled on the same ladder of resolutions, scaling between them is clean and predictable, which is exactly why a resizer offers them as presets rather than asking for raw pixel dimensions.
Streaming made this ladder central to how video is delivered. Adaptive streaming encodes the same video at several resolutions at once, 1080p, 720p, 480p and lower, and the player hops between them second by second based on your connection. That seamless quality-switching you see when a video briefly goes soft and then sharpens again is the player climbing up and down the very same resolution ladder these presets are built on.