Compress JPG Images Online

On a 5,486 KB photograph the default setting removed 88% of the bytes, leaving 631 KB. The exact number depends on the picture: a noisy, detailed photo compresses less than a smooth one. You do not have to guess, because the estimated size updates as you move the slider, before you commit to anything.

At quality 70-80, the difference is barely noticeable. Lower quality settings will show more compression artifacts.

Yes. Upload in bulk, set your quality, and download all compressed files.

80 is the default and it is where the table above says the value is: most of the saving has already arrived and the similarity to the original is still 0.982. Go to 85 or above for photos you will print or crop into later. Drop to 60 or 70 for thumbnails, where nobody is looking closely. Below 60 the file stops shrinking much while the damage keeps accumulating, which is the worst trade on the slider.

Much less than people expect, as long as the quality setting does not change. We compressed a photograph five times in a row at the default: the file stayed at 477 KB every pass, and the fifth pass measured 57.9 dB against the first, which is a difference no eye will find. The damage happens on the first pass and later passes at the same setting mostly re-encode the same decisions. What does destroy an image is lowering the quality each time, because every pass then throws away detail the last one kept.