Compress Image

Down to about 70% quality most photographs are indistinguishable from the original at normal viewing size, while the file is a third of what it was. The wiper is there so you can find that point yourself rather than trust a number.

Lower the quality and watch the wiper: the file shrinks steadily while the picture holds, up to a point you can see. Resizing first usually optimises more than quality alone.

Resize first. A 4000 pixel photo displayed at 800 is carrying twenty-five times the pixels it needs, and no amount of quality reduction fixes that.

No. The re-encoding runs in your browser using canvas. This site has no backend, so the photo never leaves your device — worth knowing given that photos routinely carry GPS coordinates.

For photographs, somewhere between 70 and 85 is almost always the right answer. Above 90 you pay a lot of file size for detail nobody can see; below 60 the artefacts become obvious.

Because the original was already well compressed. Re-encoding an image that has already discarded detail can spend more bits describing its existing artefacts than the original used. Keep the file you have.

WebP is roughly 25–35% smaller than JPEG at the same visual quality and keeps transparency. Every current browser supports it. Choose JPEG only when something older has to open the file.

Because PNG is lossless — there is no quality to trade away. It is the right format for screenshots, line art and transparency, and the wrong one for photographs, where it will usually be larger than the original.

Yes, as a side effect. The image is redrawn through a canvas, which holds pixels only, so EXIF data including GPS is not carried into the output. To do that deliberately, use the EXIF tool, which shows you what was there first.

Not yet — this tool handles one at a time so the quality trade-off stays visible for each image. Batch compression at a fixed quality tends to over-compress some pictures and under-compress others.

No fixed limit, but the whole image is held in memory as raw pixels while it is processed. A 50-megapixel photo needs around 200 MB of RAM at that stage, which a phone may refuse.

Yes, all three, though they do not behave alike. Compress JPG and compress JPEG name the same format, and the quality slider drives it directly. Compress PNG has no slider because PNG is lossless — the saving comes from re-encoding, so it is smaller but never dramatic. WebP takes a quality setting like JPEG and usually lands smallest of the three. If you want to compress a photo further than the slider allows, resize it first: half the width is a quarter of the pixels.

They name the same goal by different routes. Reduce image size and shrink image both usually mean the file, and that is what this does — compress images, compress photo or compress picture, all the same operation. If you mean the dimensions instead, resize is the tool: halving the width removes three quarters of the pixels and beats any quality slider.