JPG and PNG are the two image formats everyone has on their machine, and they are built on fundamentally different ideas. JPG throws away detail your eye is unlikely to miss, in exchange for small files. PNG throws nothing away, in exchange for larger ones. Once you understand that trade — and the one feature that actually separates them, transparency — choosing between them stops being a matter of opinion.
How JPG compression works
JPG is lossy: it analyses the image in blocks, discards information the human eye is poor at detecting, and stores what remains compactly. A quality setting of 80–90% typically produces files several times smaller than lossless formats with no visible difference. The costs appear over time: every re-save re-compresses the image and stacks a little more loss on top (generation loss), and sharp edges — text, logos, fine lines — develop visible halos called artefacts. There is also no transparency: where a JPG needs "nothing", it stores a colour.
How PNG works
PNG is lossless: every pixel is preserved exactly, forever, through any number of saves. It also supports full alpha transparency — pixels can be partially see-through, which is what lets a logo sit cleanly on any background. The price is size: a photograph stored as PNG can be 3–5× larger than the same photo as JPG, because photographic gradients are exactly what lossless storage handles worst. For flat graphics — logos, icons, screenshots, charts — PNG is very efficient, because large areas of identical colour compress well.
The decision rule
- Photographs → JPG. Gradients and noise are what JPG compresses best; artefacts are invisible at sane quality levels.
- Graphics with sharp edges → PNG. Text, logos, UI screenshots and diagrams stay crisp; JPG would fuzz every edge.
- Need transparency → PNG, always. JPG cannot do it at all.
- Saving the same image repeatedly → PNG. Lossless means generation loss never happens.
- Modern web use → consider WebP. It does lossy and lossless, supports transparency, and typically beats JPG by 25–35% at equal quality.
Converting between them
JPG to PNG is always safe — lossless storage can't degrade what it receives (though it can't restore what JPG already discarded). PNG to JPG needs care: transparency must be flattened onto a chosen background colour first, and once it's JPG, the transparency is gone for good. That asymmetry is worth internalising: PNG is the safe master copy; JPG is the delivery copy. Keep the PNG for anything you'll edit again, export JPG for the web or email. The image converter handles both directions in one drop.
One step further
If you manage a website, the practical hierarchy today is: PNG for UI graphics and anything transparent, JPG for photos where support matters most, and WebP wherever your audience's browsers allow (which in 2026 is effectively everywhere). The full format-by-format table — compression type, transparency, best-for and typical sizes — is in the JPG vs PNG comparison, and converting a whole folder of images takes one batch on the homepage uploader.