If you maintain a website and you’re still serving PNG images for anything other than the simplest icons, converting to WebP is one of the more reliable ways to shave meaningful weight off your pages without giving up anything most visitors would notice — including the transparency that’s usually the whole reason you’re using PNG in the first place.
What makes WebP a genuine upgrade here, not just a different format
PNG earned its place as the default format for logos, icons, and graphics with transparency because it’s lossless and supports an alpha channel — two properties JPG never had. WebP was designed, in part, specifically to do everything PNG does, but more efficiently: it supports both lossless compression and an alpha channel exactly like PNG, while generally compressing the same image data into a meaningfully smaller file. This isn’t a tradeoff in the way that, say, converting to JPG would be — you’re not giving up transparency or losslessness to get the size benefit, assuming you stick with WebP’s lossless mode, which is the natural choice when converting from an already-lossless PNG.
Where the actual size savings come from
WebP’s compression algorithm, particularly in lossless mode, generally does a better job than PNG’s at finding and exploiting redundancy in image data — repeated patterns, runs of similar colors, structural regularities common in UI graphics, icons, and logos. The result, for most typical PNG images, is a WebP file noticeably smaller than the PNG it came from, frequently by more than half, while remaining pixel-for-pixel identical if you use lossless encoding. For images where you’re willing to accept a small amount of quality tradeoff in exchange for an even smaller file, WebP’s lossy mode (similar in concept to JPG’s quality setting, but compatible with transparency) can shrink things further still.
The one place this matters less: outside the browser
WebP’s main limitation isn’t quality or compression — it’s that support outside web browsers remains less consistent than PNG’s. If these images are destined purely for a website, where browser support for WebP is now close to universal, that limitation essentially doesn’t apply. If you’re also distributing these graphics through channels outside the browser — handing files to a print shop, sharing assets with someone using older design software, attaching to certain business tools — PNG’s broader, longer-established compatibility may still be the safer choice for those specific uses, even at the cost of a larger file.
A sensible default for most website work
For the common case — optimizing images that visitors will see in a browser, which is the overwhelming majority of website imagery — converting PNG to WebP is a safe, effective default that keeps everything PNG was good at (transparency, losslessness if you want it) while meaningfully reducing how much data visitors need to download, which feeds directly into faster page loads and better Core Web Vitals scores.