How to use
- Drop in or select a video file (MP4, MOV, WebM, and other common formats).
- Enter a target width and height in pixels, or leave one field blank to keep the aspect ratio.
- Click Resize and wait for the ffmpeg engine to process your video locally.
- Download your resized MP4 video.
Frequently asked questions
Will my video be uploaded to a server?
No. Your video is processed entirely in your browser with ffmpeg.wasm and never leaves your device — 100% private, with no uploads.
What video formats can I resize?
You can load common video formats such as MP4, MOV, WebM, MKV, and AVI. Whatever you feed in, the resized result is exported as an MP4 file.
How do I keep the original aspect ratio?
Leave one of the two fields blank. That dimension is calculated automatically from the value you entered, so the video keeps its proportions and is not stretched.
Why does the first run take a while?
On the first use the tool downloads the ~30 MB ffmpeg engine. After that it is cached in your browser and runs faster, even offline.
Is there a file size or resolution limit?
There is no fixed limit, but since resizing happens in your browser, very large videos or high resolutions use more memory and take longer. Smaller clips process fastest.
Can I upscale a video to a larger size?
Yes, you can enter dimensions larger than the original to upscale, though upscaling cannot add detail that was not in the source. Widths and heights are rounded to even numbers as MP4 encoding requires.
About this tool
Free online video resizer. Scale a video to a new width and height or change its resolution entirely in your browser with ffmpeg.wasm — nothing is uploaded.