Resize any image, instantly.

Resizing, cropping and compressing are three different things

People usually say "resize" when they mean one of three operations, and the difference decides whether the result looks right. Resizing changes the pixel dimensions and keeps the whole picture. Cropping cuts part of the picture away to reach a shape. Compressing leaves the dimensions alone and reduces the file size by discarding detail. If an upload is rejected for being too large, the fix is usually the first or the third — and if it is rejected for the wrong shape, only the second will do it.

Aspect ratio is the arithmetic underneath all of this. A 4000 × 3000 photo is 4:3; asking for 1080 wide keeps the shape only if the height lands at 810. Force it to 1080 × 1080 instead and the picture stretches. That is why the height updates on its own when the ratio is locked — and why unlocking it is something to do deliberately, not by accident.

Downscaling is safe. Going from 4000 pixels wide to 1080 throws away information you cannot get back, but the result is genuinely sharp because every output pixel is averaged from several real ones. Upscaling is the opposite: a 500-pixel image asked to fill 2000 pixels has no extra detail to draw on, so the software invents it. The file gets four times larger and the picture gets softer. If you need a large image, start from a large original.

The sizes worth knowing, because they cover most of what people are resizing for: Instagram square 1080 × 1080, portrait 1080 × 1350, Reels and Stories 1080 × 1920. A YouTube thumbnail is 1280 × 720. A link preview image — the one that shows when a page is shared — is 1200 × 630. A favicon is 32 × 32 or 512 × 512 for the modern manifest version.

Dimensions and file size are related but not the same. A 1080-pixel JPEG saved at maximum quality can easily be larger than a 2000-pixel one saved sensibly, which is why an image that is already the right shape may still need the quality slider rather than the dimensions. For photographs, JPEG at around 80–90% quality is usually indistinguishable from the original at a fraction of the size; for screenshots, flat graphics and anything with text, PNG or WebP holds up far better.

The resizing happens on a canvas inside your browser. Nothing is uploaded, nothing is stored on a server, and the file never leaves your device — so a passport photo, a signed document or a screenshot with private information stays where it is.