Lossy vs. Lossless Compression, Explained Simply
2026-06-02
Compression makes image files smaller, but it comes in two fundamentally different flavors — lossy and lossless — and knowing which is which explains a lot of everyday image behavior: why a JPG gets blurry if you save it too many times, why a PNG logo stays perfectly crisp, and why WebP can do both.
Lossless: smaller, but identical
Lossless compression shrinks a file by storing the same information more efficiently — like zipping a document. When you open it, you get back every original pixel, exactly. Nothing is thrown away. PNG is lossless, which is why it's perfect for logos, icons, screenshots and line art where every edge must stay sharp. The trade-off is that lossless files are larger, because there's a limit to how much you can compress without discarding anything.
Lossy: much smaller, by throwing detail away
Lossy compression makes files dramatically smaller by permanently discarding detail the human eye barely notices — subtle color shifts, fine texture. JPEG is lossy, which is why it's ideal for photographs and why you can shrink a photo by 80% with no obvious change. The catch: each time you re-save a JPG, it discards a little more, so repeatedly editing and re-saving slowly degrades it. Save your edits in one pass when you can.
How to choose
For photos, use lossy — compress a JPG, or convert to WebP for even smaller files. For graphics with sharp edges or transparency, use lossless — keep PNG, or use lossless WebP. And if a "PNG" is really a photograph, convert it to JPG to switch from lossless to lossy and shrink it dramatically. WebP is popular precisely because it offers both modes in one modern format.