Compress image
Shrink your photos in seconds. All the processing happens right in your browser: the image never leaves your device.
JPG, PNG or WebP, even very large photos
How image compression works
The tool re-encodes your image at a quality level that dramatically cuts the file size while keeping it looking almost identical to the original. At 75% quality, most photos shrink by 60-80% with no difference visible to the naked eye.
Why compress your images?
Lighter photos mean faster websites, emails that send without attachment errors, more free space on your phone and quicker uploads to social media and marketplaces. It's the first step for anyone publishing content online.
What JPEG actually throws away
It does not reduce the pixels: it throws away the details the eye notices least. It divides the image into squares eight pixels across, breaks them into frequencies and keeps the high ones — that is, the abrupt transitions — only roughly. That is why a landscape photo takes compression very well and an image with text in it falls apart immediately.
The typical flaw is called a blocking artefact and shows on sharp edges: a dirty halo around letters, or the chessboard that appears in skies when quality is too low. If the squares are visible in a compressed photo, quality has dropped below the useful limit and it is better to go back up ten points than to accept it.
Why you do not compress twice
Every save in JPEG recompresses from scratch what had already been compressed, and the damage accumulates: after a few rounds the photo has halos everywhere, even though each single pass looked like high quality. It is why an image doing the rounds of several chats arrives unrecognisable.
The practical rule is to keep the original and generate every version from it, instead of compressing the compressed version. And if a photo has to be cropped or corrected, make all the edits first and compress once only, at the end.
Which format for what
The JPEG is for photographs, that is for images with continuous gradients. PNG is for graphics, text, screenshots and anything with sharp edges or transparency: on a photograph it produces enormous files, on a screenshot it produces smaller and sharper ones. WebP does both and weighs twenty to thirty per cent less, and is by now supported by every browser.
The mistake seen most often is a screenshot saved as JPEG: the text goes blurry and the file is not even lighter, because JPEG works badly precisely on sharp edges. With a screenshot, PNG is the right choice, and if the file stays big the problem is the resolution, not the format.
How much to compress, in practice
For a website the useful band is between seventy and eighty per cent quality, and the size to watch is the one per image, not the total: a page with ten one-megabyte photos does not open on a mobile connection. For an email attachment it is wise to stay well below the stated limit, because attached files grow by roughly a third.
The calculation almost nobody makes is that reducing dimensions counts for more than compressing: halving width and height removes three quarters of the pixels, and no JPEG quality setting does as much without ruining the image. If a phone photo has to go into a document, the first step is resizing it.
Nearby tools
To hit an exact size there is Compress to a target size, to change dimensions Resize photo and to change format Convert image. To see how much a photo weighs and measures Photo dimensions and info, and to remove hidden data Remove metadata.