Resize Image scales an image to a new pixel size entirely in your browser, using the Canvas API to redraw the decoded image at the target dimensions before re-encoding it in its original format. No file is ever uploaded to do this.

Two resize modes cover the common cases: exact dimensions, where you type a target width and/or height (with an aspect-ratio lock so the image never looks stretched unless you explicitly unlock it), and percentage scaling, which is often faster when you just want "half size" or "twice as big" without doing the pixel math yourself.

When resizing a batch of images together, each file is scaled from its own original dimensions rather than forced to one uniform output size, so percentage mode in particular stays correct across a batch of differently-sized photos.

It's worth understanding what resizing can and can't do to image quality. Shrinking an image is generally safe — the Canvas API's image smoothing averages nearby pixels down into fewer output pixels, which is exactly how downscaling is supposed to work and rarely produces visible artifacts. Enlarging an image is a different story: there's no real detail to recover that wasn't in the original file, so the browser is left interpolating between existing pixels to fill in the extra space. The result is a larger file that looks noticeably softer than a photo genuinely captured at that resolution — useful when you need a specific pixel size for a form field or template, but not a substitute for a higher-resolution source image.

Because resizing only changes dimensions and re-encodes at the same quality settings as the source format, file size scales roughly with pixel count — halving both width and height cuts total pixels (and typically file size) to roughly a quarter of the original. If your actual goal is a smaller file rather than smaller dimensions specifically, the Compress Image tool targets file size directly without changing the image's dimensions at all.