Compress an image

Compress an image is a free tool that runs entirely in your browser, with no data ever sent to a server. Shrink a JPEG, PNG or WebP file, down to a target size in kilobytes.

How it works

Your image is decoded by the browser, redrawn on a canvas, then re-encoded at the compression level you chose. The file never leaves your disk, and no copy is kept.

Quality or target size: which to choose

Quality mode keeps a consistent look across images, but the final size varies with content. Target size mode does the opposite : it automatically finds the best quality that stays under the requested size. Useful when a site enforces a limit, like a 500 KB attachment.

Which format gives the best result

At equivalent perceived quality, WebP is usually 25 to 35% lighter than JPEG, and it supports transparency. JPEG remains the most compatible choice for a photo. PNG suits screenshots, logos and images with a transparent background, but it has no quality setting : compressing it really means changing format.

What this tool does not do

This tool does not read HEIC photos (the default on some iPhones) : convert them to JPEG on the device first. On a PNG, compression changes format rather than truly shrinking the file, since the browser cannot produce a reduced-palette PNG.

Frequently asked questions

Are my images sent to a server?

No. All the processing happens in your browser. You can disconnect from the internet once the page has loaded : the tool keeps working.

Is there a size or count limit?

No limit set on our side. The only constraint is your device's memory. On a computer, batches of dozens of photos go through without trouble ; on a phone, smaller batches work best.

Does compression damage the image?

JPEG and WebP are lossy formats : some information is discarded. Between 75 and 85% quality, the difference is invisible to the eye for a photo. Below 60%, flat areas and edges start to degrade.