Image compression is mostly an art of picking the right format and the right quality slider. Here is the practical version, free of jargon.
JPG: the everyday choice
JPG is lossy. You will lose some data every time you save. For most photos a quality of 75 to 82 looks identical to the original on screens but is roughly half the file size. Anything below 65 starts to show blockiness in flat areas like skies.
PNG: only when you need transparency
PNG is lossless, so compression is limited. If your image is a photo and you do not need transparency, convert it to JPG or WebP, and the file size drop is huge with no visible loss.
WebP: the modern default
WebP at quality 80 typically beats JPG at quality 85 on both quality and size. Every modern browser supports it. Use it whenever you have control over the format.
The two-step approach
- Open Universal Image Compressor and convert to WebP at quality 80.
- If the result is still too large, use Compress to Specific KB to target an exact file size.