What video resolution is
Resolution is the number of pixels across and down in each frame of a video, usually written as width by height. A 1920 by 1080 video has 1920 pixels across and 1080 down. More pixels can hold more detail, but they also mean larger files and more work for a device to play.
Changing resolution means scaling every frame to a new size. This tool takes a target width and works out the height itself so the picture keeps its proportions. Internally the height is set automatically and adjusted to an even number, which video encoders usually require. For example, scaling a 1920 by 1080 video to a width of 640 gives a height of 360.
Because every frame is rescaled and the video is encoded again, the process takes time and creates a new encode of your footage.
Why you might change it
The main reason is to make a file lighter. Footage recorded at a high resolution can be too big to email or upload, and playing it on a small screen gains nothing from the extra pixels. Scaling down to a smaller width is a common first step before sharing.
Another reason is to match a requirement, such as a platform or an editing project that expects a certain width. Making several clips the same size can also help before you join them, since the Merge Videos tool works best when the clips match.
Scaling up is possible, but it does not add detail. Enlarging a small video just spreads the existing pixels over a bigger frame, so it will look soft.
How to change the resolution with this tool
- Drop a video file onto the upload area, or click it to browse.
- In the Target width (px) box, enter the width you want. It starts at 1280.
- Click Run. The first time, the video engine downloads (roughly 30MB) and is cached afterward.
- Wait for the progress bar, then play the preview to check the size and quality.
- Click Download. The file is saved as your original name followed by
-change-resolution, as an MP4.
There is no height field and no list of presets. Only the width is entered, and the height follows from the original proportions. If you want a different aspect ratio, use the Crop Video tool as well.
Tips and limits
Work from the original file whenever you can. Scaling an already scaled copy stacks up quality loss, since each pass is a new encode.
The tool does not check your number, so keep it positive and sensible. An empty or zero width is likely to make the job fail, and a very large width produces a huge frame that can use a lot of memory. Entering a width larger than the original enlarges the video without adding detail.
The output is always MP4, using the encoder's default settings, so there is no quality or bitrate control. If your aim is only a smaller file at the same size, the Video Compressor offers a quality slider instead.
Everything runs locally in the browser, so the speed depends on your device and the length of the video. Long or high-resolution clips can take a while and may run out of memory, in which case the tool shows an error message. Trying a shorter clip is the quickest check.