Image tool
Compress image
Every slider you move re-encodes the picture and shows you the real size, not an estimate. Or skip the slider: say "under 500 kB" and let it find the setting.
Drop an image here
Or press to choose one.
nothing is uploaded — this page does the work
The number under the slider is real
Most compressors show you a quality percentage and make you guess what it means in kilobytes. This one re-encodes the image every time you move the slider and shows you the size that actually came out. The value you see is the file you will get.
It costs a few milliseconds per move on a laptop and is worth it: "quality 70" means nothing, and "1.2 MB → 340 kB" means everything.
Aiming at a size instead of a quality
Almost nobody wants a quality level. They want to get under the 2 MB limit on an upload form, or under 500 kB so a page loads quickly on a phone.
Type the number, press the button, and the tool binary-searches the quality parameter — at most nine encodes — for the highest quality that still fits. If even the lowest quality is too big, it says so and tells you that reducing the width as well is the lever that will work: halving the width takes roughly three quarters off the file, which no quality setting can match.
Where the savings come from
Two dials, and they do different things. Quality throws away detail the eye is bad at noticing — between 90 and 75 most photographs look identical and the file halves. Below about 60 you start to see blocking in skies and around text. Dimensions throw away pixels, and that is a much bigger lever: a 4,000-pixel photograph shown in a 1,200-pixel column is carrying three times more width than anything will ever display.
If a photograph is enormous, capping the width is almost always the right first move, and the quality slider is the fine adjustment afterwards.
A note about PNG
PNG is lossless, so the quality slider does nothing to it. Choosing PNG for a photograph will produce something larger than the JPEG you started with. The tool will let you do it and will show you the percentage going the wrong way.
PNG in this list exists for the case where you want to cap the dimensions of a screenshot or a logo without introducing artefacts. For photographs, JPEG or WebP.
What is not preserved
The same canvas rule as the rest of the image tools: EXIF, GPS coordinates, camera information and the colour profile do not survive. For photographs headed to the web that is a privacy improvement. For anything colour-managed it is a limitation, and the tool would rather tell you now than have you find out from a printer.