PNG vs WEBP: which lossless-friendly format wins?
Both handle transparency. Only one of them can also shrink a photo-heavy image by 60-80%. Here is when that gap actually matters.
Published Updated 6 min read
PNG and WEBP are the two formats that both support a real alpha channel, so the transparency question doesn't decide between them the way it decides between JPG and PNG. The real difference is compression: PNG is always lossless, while WEBP can compress its colour data lossily while keeping the alpha channel sharp. That single feature is where almost all the size difference comes from.
When they're basically the same size
For flat-colour graphics — simple icons, logos with few colours, UI elements — PNG's lossless compression is already efficient, and converting to WEBP often saves very little, sometimes nothing. If a file is a few kilobytes either way, the conversion step isn't worth the extra build complexity.
When WEBP pulls ahead dramatically
The gap opens up as soon as an image has photographic detail behind the transparency: a product cut-out with a soft drop shadow, a portrait with real hair strands, an illustration with gradients. PNG has to store every one of those pixels losslessly; WEBP can compress the colour channel the same way it compresses a photo, while the alpha edge stays crisp. Cuts of 60–80% on this kind of image are typical, not exceptional.
| Image type | PNG size (approx.) | WEBP size (approx.) |
|---|---|---|
| Simple flat-colour icon, 128×128 | 3–6 KB | 3–6 KB |
| Logo with soft shadow, 800×800 | 120–200 KB | 40–70 KB |
| Product cut-out with hair/fur detail, 1600×1600 | 2–4 MB | 400–800 KB |
| Full-screen app screenshot with UI | 500 KB – 1.2 MB | 250–500 KB |
Where PNG still wins
- Older desktop software and some print workflows still don't open WEBP directly.
- If the image is going into another lossless editing pipeline, PNG avoids stacking any lossy compression before the final export.
- Email clients have patchier WEBP support than browsers — for embedded email images, PNG or JPG is the safer default.
A simple rule
If the image is going on a modern website and has any photographic or gradient content behind the transparency, convert to WEBP and check the saving. If it's a small flat icon, or the destination doesn't reliably support WEBP, PNG is fine as it is and converting adds a step for little benefit.
Tools for this
- PNG to WEBPUse it the standard move for transparent PNGs that are heavier than they need to be.
- WEBP to PNGUse it when an old editor or CMS only accepts PNG.
- WEBP CompressorUse it to tune quality once you've committed to WEBP.
- PNG CompressorUse it to check whether a resize or palette change helps before converting.
Keep reading
- JPG vs PNG: which one should you actually use?One throws away detail to stay small, the other keeps every pixel and every transparent edge. Here is how to pick without guessing.
- JPG vs WEBP: is it worth converting your images?WEBP typically saves 25–35% over an equivalent JPG. Here is where that saving is real, where it isn't, and what you give up.
- How to choose the right image format, every timeJPG, PNG, WEBP, GIF, SVG, TIFF — each one was built for a specific job. Pick by content type and you'll rarely get it wrong.