What is an image compressor?
An image compressor makes a picture take up less storage while keeping it close to the original.
SizeUply does that in your browser. Choose a compression level, compare the before and after, and download the new file. The original file on your device is left untouched.
How image compression works
JPEG and WebP can discard detail that is hard to see. A lower quality setting makes a smaller file and a softer image. PNG is lossless, so a normal PNG export keeps the pixels and often cannot reach a tiny file size.
Resizing is separate. A 4000-pixel photo shown at 800 pixels is still downloaded at full size unless you create a smaller version. The useful reductions usually combine a sensible pixel size with JPG or WebP.
When to use JPG
Use JPG for photographs when the destination does not need transparency.
It is widely supported. A balanced quality setting is often enough for email and forms. JPG cannot store transparency; this tool fills transparent areas with white. Saving a JPG again and again can soften detail, so start from the original when you can.
When to use PNG
Use PNG for logos, screenshots, diagrams, and images that need transparency or sharp edges.
Because it is lossless, it will not add the blocky artifacts a low-quality JPG can show on text. That same behavior means PNG is a poor way to force a file down to 100 KB. If a PNG is too large, WebP is usually the realistic choice.
When to use WebP
Use WebP when you want a smaller file than JPG or PNG and the destination accepts it.
Current versions of Chrome, Firefox, Safari, and Edge can display WebP. Converting to WebP does not restore detail already lost in a JPG. It stores the image you provide more efficiently, and it can keep transparency.
How to reduce image size
Check the dimensions first, then compress.
A camera photo may be several thousand pixels wide when the page only needs about 1600. Resize, then compress. Switch a heavy photograph from PNG to JPG or WebP. If the preview looks soft, step back to Balanced. If the file is still too big, try a target such as 200 KB or 500 KB.
How to compress an image to 100 KB
Open Exact size, choose 100 KB, and keep WebP or JPG as the output.
The tool encodes the image, checks the file size, and adjusts quality. If quality would fall too far, it reduces the pixel dimensions and tries again. A large lossless PNG often will not reach 100 KB. In that case the tool says so and can switch the output to WebP.
Why browser-based image processing is useful
The picture does not have to leave your device for this tool to work.
That helps with IDs, drafts, and family photos you would rather not send to a server. Very large images can still run into the memory available to the browser tab. If that happens, that file stops with an explanation and the rest of the page stays usable.