Video Resizer

About this tool

Pick how to resize: to a standard height (2160p, 1440p, 1080p, 720p, 480p, 360p, 240p), by width, by height, by a percentage of the original, or to an exact width and height. For all but the exact option the other side is worked out so that the shape of the picture stays the same, and every size is rounded down to an even number as the H.264 format requires. The picture is scaled with a high-quality filter (Lanczos) and saved as MP4; the sound is copied unchanged. Making a video smaller lowers the file size and the work needed to play it, which helps for the web and for messages. Making it larger does not add detail: it only makes a bigger copy of the same picture. Sizes above 7680 pixels on a side are refused because a browser cannot encode them. We checked the ffmpeg commands this tool builds by running them with a real ffmpeg on test clips and measuring the results (sizes with ffprobe, picture content with ImageMagick, sound with a spectrum and loudness meter), and the page itself in a browser with the real ffmpeg.wasm engine. The first use downloads the ffmpeg engine (about 25 MB), which then stays in your browser cache. It needs a current desktop Chrome, Edge or Firefox; large videos use a lot of memory, and very long clips can fail on small devices. Your file is processed in your browser with ffmpeg and never uploaded.

How to use it

1. Choose a video.
2. Choose the new size.
3. Press Process.
4. Download the resized MP4.

Common problems

The file is not much smaller

Resizing lowers the number of pixels, but the quality setting decides most of the size. Use the video compressor as well.

The picture looks stretched

Use one of the options that keep the shape (standard size, width, height or percent). Exact size can change the shape.

It says the result would be too large

Choose a smaller size. Browsers cannot encode pictures larger than 7680 pixels on a side.