About the free video resizer
This tool changes a video's resolution entirely on your own device. It reads the file with WebCodecs, the hardware video engine built into modern browsers, scales every frame to the target size, and re-encodes the result locally. There is no upload, no queue, and no server between you and your footage, which is why the tool is unlimited: resizing a video costs us nothing, so nothing is metered. The aspect ratio is always preserved, and dimensions are rounded to even numbers because video codecs require them.
The presets cover the sizes that matter in practice. 1080p is the safe default for sharing and social platforms, 720p is the workhorse for messaging and email where file size matters more than pixel count, and 480p is for previews and slow connections. The custom width option handles everything else, from odd player dimensions to embedded video slots in websites and presentations.
Downscaling: the strongest compression lever
Halving a video's resolution roughly quarters the pixels per frame, which means the encoder needs far less bitrate to make the result look clean. If your real goal is a smaller file, resize down first and then run the result through the free video compressor with a target size. A 720p file at a healthy bitrate almost always looks better than a 4K file starved to the same size. Downscaling also genuinely improves the look of shaky or noisy footage, because scaling down averages away noise the way no filter can.
Enlarging: why plain resizing is not enough
Resizing a video up is possible with this tool, but it cannot create detail that was never recorded. Stretching 480p to 1080p just spreads the same information over more pixels, so edges go soft and compression artifacts get magnified. If you need a small or old video to actually look sharper at a larger size, that is an AI job: Upsampler's free AI video upscaler reconstructs real detail frame by frame, and the premium Video Upscaler extends that to long clips and 4K output. Use plain resizing for shrinking, AI upscaling for enlarging.
Formats, browsers, and limits
The tool accepts MP4 (H.264/H.265), MOV, WebM, and MKV. MP4 and MOV come back as MP4, WebM and MKV come back as WebM. It works in current versions of Chrome, Edge, Safari, and Firefox, and tells you immediately if your browser lacks WebCodecs support rather than failing halfway. Files up to around 2 GB process reliably on typical hardware; the only real ceiling is your device's memory. If you only need part of the clip at the new size, cut it first with the free video trimmer so the re-encode spends time only on the seconds you keep.