About the image compressor
Two things reduce a file's size, and they are not equally effective. Lowering quality discards detail within each block of the image; reducing the dimensions discards pixels outright. For anything destined for a screen, scaling to the size it will actually be displayed at saves far more than any quality setting.
Quality below about 60 starts to show visibly on photographs - blocky skies and haloes around hard edges. Between 75 and 85 is where most of the saving is available for almost no visible cost.
Frequently asked questions
- Is my image uploaded anywhere?
- No, and this is the whole point of the tool. The file is read by the page, processed by your own browser and handed straight back to you. It never reaches a server, there is nothing to delete afterwards, and you can disconnect from the network before choosing a file and it still works.
- Why did my file get bigger?
- Almost always because the output format was PNG. PNG is lossless and stores photographs poorly, so a JPEG re-saved as PNG can easily triple in size. It is reported rather than hidden when this happens.
- What quality should I use?
- Start at 80. Photographs tolerate 75 to 85 with no visible loss and most of the size saving. Screenshots, logos and anything with sharp text do far better as PNG, where quality does not apply at all.
- Does compressing twice make it smaller again?
- It makes it worse, not smaller. Lossy compression discards information permanently, and re-compressing an already compressed image throws away more detail for very little further saving. Always compress from the original.
- Is there a size limit?
- 25 MB, and a warning above 10 MB. The constraint is memory rather than bandwidth: an image has to be decoded into a canvas to be worked on, and a 100-megapixel photograph needs far more memory decoded than it does on disk. A clear refusal is better than a tab that stops responding.
Related image tools
How your data is handled
Everything happens on your device. There is no upload, no storage and no logging. Closing the tab clears everything you entered.