Image resizer

How to use it

1. Choose an image. It opens in this tab and is never uploaded.
2. Type a width or a height, or set a scale percentage. With the aspect ratio locked, the other side follows.
3. Pick the format to export, and a quality for JPEG or WebP.
4. Download the resized image.

Your image is not uploaded anywhere

This tool runs entirely in your browser. The file you choose is opened by the tab you are reading this in, resized by the same browser that draws this page, and handed back to you — it is never sent to Sellstamp, and there is no server here that could receive it. That is worth stating plainly, because most free image tools do the opposite: they upload your file, process it, and keep it for some period described in a privacy policy you did not read.

Aspect ratio, and what happens when you turn it off

With the ratio locked, typing one dimension derives the other from the original proportions, so the image is scaled. Unlock it and the image is stretched to whatever two numbers you give — which is occasionally what you want and much more often how a product photo ends up subtly, unaccountably wrong. If you need an exact non-matching size without distortion, resize to cover it and crop the rest.

Which format

PNG is lossless and keeps transparency: logos, screen shots, anything with flat colour or a cut-out background. JPEG is much smaller for photographs and has no transparency. WebP is usually 25–35% smaller than JPEG at the same visible quality and does support transparency, and every current browser reads it. Quality 80–90 is the range where the file gets much smaller and the picture does not visibly change.

Enlarging is not the same operation as shrinking. Scaling a 400 px image up to 1200 px cannot add detail that was never captured — it only makes the existing detail bigger and softer.