Resizing changes an image's pixel dimensions; compressing changes its file size at the same dimensions — and a site, form, or API that demands specific dimensions needs the first. Type the numbers and the image is redrawn at exactly those dimensions in the browser, exported as JPEG, PNG, or WEBP. When what you actually need is a smaller file at the same size, that is the compressor's job.
Rounding, upscaling, and disappearing transparency
The lock computes the dependent dimension with standard rounding, so a 4032x3024 phone photo set to 1200 wide comes out exactly 1200x900, while a 3000x2000 image set to 1280 wide rounds to 1280x853 — one pixel off a mathematically perfect ratio, which no one will ever see. Upscaling is allowed but cannot invent detail: interpolation just spreads existing pixels, so enlarged photos look soft. Two silent conversions to watch for: exporting a transparent PNG as JPEG paints the transparent regions black, because JPEG has no alpha channel — choose PNG or WEBP to keep transparency. And a GIF loses its animation; only the first frame is resized.
Step by step
- Drop or select an image. Anything your browser can decode works — JPG, PNG, WEBP, and GIF are the common cases. The original dimensions appear next to the preview.
- Type a new width or height. With the aspect-ratio lock on (the default), the other dimension is computed for you; unlock it only if you deliberately want to stretch or squash.
- Pick the output format. JPEG is the default; the quality slider (10-100) appears for JPEG and WEBP and is hidden for PNG, where it would have no effect.
- Download. The file arrives as resized.jpg, resized.png, or resized.webp.
Pair this with the image compressor: resize first to remove pixels, then compress the result — dimension cuts shrink files far more than quality cuts do.