Resize image
Change image dimensions on your device. Drop as many as you like.
Runs on your device. The file is never uploaded.
Resize image scales a JPG, PNG or WebP to the pixel size you ask for and names the result with the dimensions it ended up at, such as photo-800x600.jpg. Leave one box blank and that side follows from the original proportions. Enlarging only resamples what is already there; Upscale image is the one that reconstructs detail.
Questions
Does resizing upload my image?
No. Decoding, resizing and encoding all run in a Web Worker on your device. The resize itself is the jSquash resize WebAssembly module, the same family of codecs used by the rest of these image tools. Nothing is uploaded and nothing is stored, and the page works offline after the first visit.
How do I keep the aspect ratio?
Fill in one dimension and leave the other blank. Give only Target width and the height is worked out from the original proportions, rounded to a whole pixel and never below 1. Give only Target height and the width follows the same way. Fill in both and the image is squashed to exactly those numbers, aspect ratio and all.
Why does it say "give a width, a height, or both"?
Because both boxes were left empty and there is nothing to resize to. Both fields default to blank on purpose, so the tool never silently picks a size for you. Type a number into at least one. Decimals and zero are rejected too, with "width must be a whole number greater than 0" naming whichever field was wrong.
Can I make a small image bigger with this?
You can ask for a larger size and you will get a larger file, but no new detail. This is an ordinary resampling step, so enlarging a 400px photo to 1600px gives you a soft, stretched version of what was already there. Upscale image is the tool that reconstructs detail, using a super-resolution model.
What is the resized file called?
Your name with the final pixel size appended, such as photo-800x600.jpg. The format is kept from the input, so a PNG stays a PNG. JPG and WebP outputs use the Quality option, which defaults to 80; PNG ignores it. The page also shows the before and after dimensions for each file.
Which formats work here?
JPG, PNG and WebP, matched on the file extension. Anything else is refused with "only JPG, PNG and WebP are supported" before it is read. You can drop many files at once and every one gets the same target size, which means a batch of mixed shapes will not stay proportional unless you leave one dimension blank.