When PNG is the wrong format
PNG is lossless, which is perfect for graphics and wrong for photographs. A photograph stored as PNG carries megabytes of imperceptible detail that JPG's perceptual compression discards for free. The practical cases that bring people here: screenshots too large to email, AI-generated images that export as PNG, and upload forms with strict size limits. In all three, JPG at 85 to 90% quality looks identical and weighs a tenth as much.
Picking a quality value
The slider maps directly to the JPEG encoder. 90% is the safe default: visually transparent for photos and screenshots alike. 80 to 85% saves another third of the size and remains clean for photos, though fine text starts to soften. Below 70% ringing artifacts appear around edges. If you find yourself pushing quality to 100% to preserve exact pixels, that is a sign you actually want PNG or lossless WebP instead.
Common questions
How much smaller will my files get?+−
For screenshots and photos saved as PNG, typically 70 to 90% smaller. A 4 MB full-screen PNG screenshot commonly becomes a 300 to 600 KB JPG at 85% quality. Graphics with few colors shrink less dramatically because PNG already compresses them well.
What happens to transparent areas?+−
JPG has no transparency, so transparent pixels are flattened onto a white background during conversion. If you need the transparency kept, stay with PNG or convert to WebP instead.
Will text in screenshots stay readable?+−
At 85 to 95% quality, yes. JPG compression is weakest around sharp, high-contrast edges like text, so avoid dropping below 80% for text-heavy screenshots. For pixel-perfect UI documentation, PNG remains the right format.
Why does my camera photo exist as a PNG anyway?+−
Usually because an app exported it that way: screenshot tools, editors and AI image generators often output PNG regardless of content. For photographic content that PNG wrapper wastes megabytes, and converting to JPG reclaims them with no visible difference.