How to compress images without losing quality

"Compress without losing quality" is a popular request, and it deserves an honest answer. There are two kinds of compression, and understanding the difference is the key to getting the result you actually want.

Lossless compression: truly no quality loss

Lossless compression makes a file smaller while reproducing every pixel exactly. PNG and lossless WEBP work this way. The catch is that the savings are modest — typically 10–30% for a photograph — because there is a hard limit to how much you can shrink an image without discarding information. If absolute fidelity is non-negotiable, lossless is the only true "no quality loss" option, and you accept smaller savings in return.

Visually lossless compression: the practical sweet spot

What most people actually want is "no quality loss that I can see," which is a different and much more achievable goal. Lossy formats like JPG and lossy WEBP discard information selectively, and modern encoders are extremely good at discarding only what the eye will not miss. At quality 85–92, the compressed image is usually indistinguishable from the original to a human viewer, yet the file can be half the size or less. This is the setting most people should use.

Practical method

Start at quality 90 and compress. Compare the result against the original at the size it will be viewed. If you cannot see a difference — and at 90 you usually cannot — try lowering to 85 and compare again. Keep going until you can just barely perceive a difference, then step back up one notch. That is the optimal setting for that specific image: the smallest file with no visible loss.

Things that genuinely hurt quality

Two habits cause avoidable damage. First, repeatedly saving a JPG (opening, editing, re-saving) compounds the loss each time, because lossy compression is applied again and again; always edit from the original. Second, compressing an image that has already been heavily compressed adds artefacts to artefacts. Whenever possible, compress once, from the highest-quality source you have.

Try it

The compress tool on this site shows you the original and compressed sizes and lets you adjust quality interactively, so you can find the exact point where the file is small but the quality loss is invisible — all in your browser, with nothing uploaded.