WEBP is a genuinely more efficient format than PNG in most cases — smaller files at equivalent quality — but it's not universally supported yet, so converting a WEBP image back to PNG comes up whenever you hit software, a platform, or an older device that doesn't handle WEBP properly.
Why you'd need to convert away from a "better" format
WEBP support has become broad across modern browsers and operating systems, but plenty of older software, some design tools, and certain upload systems still only accept the more established formats. If you've downloaded an image as WEBP (a common default on many websites now) and need to use it somewhere that rejects that extension outright, converting to PNG is the fix — trading some file size efficiency for near-universal compatibility.
What's preserved in the conversion
If the source WEBP was saved losslessly, converting to PNG preserves that quality exactly — both are lossless formats, so nothing is discarded in the conversion. If the WEBP was saved with lossy compression, the PNG conversion locks in whatever quality that lossy compression left behind (same as converting any lossy image to a lossless format) — it won't restore detail the original compression already removed, it just stops further loss from happening.
Transparency carries over correctly
Both WEBP and PNG support an alpha channel for transparency, so if your source WEBP has a transparent background, that transparency converts cleanly to PNG — nothing needs to be redone or re-added.
Expect a larger file
Since PNG doesn't compress as efficiently as WEBP for most images, expect the converted PNG to be noticeably larger than the original WEBP file. That's the direct cost of trading WEBP's efficiency for PNG's broader compatibility, and it's worth being aware of if you're converting a large batch of images for a website that cares about load time.
The image converter handles WEBP to PNG directly in your browser, along with every other common format pair. If file size becomes a concern after converting, Compress Image can bring the resulting PNG back down without changing the format again.