The short answer: for file size, WebP wins almost every time. For compatibility and editing workflows, PNG still wins almost every time. The right question is not which format is better — it is which job you are doing. But "it depends" is only useful once you know why it depends, and that comes down to how each format compresses.
How the two formats compress
PNG does exactly one thing: lossless compression. Each row of pixels passes through a predictor filter that makes the data as repetitive as possible, then DEFLATE — the same LZ77-plus-Huffman family inside ZIP files — squeezes the result. Every pixel survives bit-for-bit. PNG was designed in the mid-1990s as a patent-free GIF replacement, and the birth of PNG explains why it was built so conservatively.
WebP does two things, because it is really two formats sharing a file extension. Lossy WebP is VP8, the intra-frame codec from Google's video compression work — block-based, frequency-domain, philosophically a cousin of JPEG. Lossless WebP is VP8L, a purpose-built lossless codec with its own entropy coding, color transforms, and spatial prediction. Google released the whole thing in 2010, and the birth of WebP has the full backstory.
Both formats support alpha transparency, but differently. PNG carries alpha as a first-class channel next to red, green, and blue. Lossy WebP bolts alpha on as a separate channel encoded losslessly alongside the lossy color data — so you get a compressed photo with a crisp transparent cutout, which neither JPG nor plain VP8 could do alone. If the distinction between the two compression philosophies is fuzzy, our explainer on lossy vs. lossless compression covers the fundamentals.
The size reality
Google's own benchmarks claim lossless WebP runs about 26% smaller than PNG on the same images. In practice, on real graphics, that number holds up:
| Image | PNG | WebP (lossless) | WebP (lossy, q80) |
|---|---|---|---|
| 1920×1080 UI screenshot | ~250 KB | ~180 KB | ~90 KB |
| Logo with transparent background | ~40 KB | ~28 KB | ~12 KB |
| 12 MP photo (for comparison) | ~20 MB | ~14 MB | ~1.5 MB |
Two things stand out. First, lossless WebP beats PNG on PNG's own turf — screenshots, logos, flat graphics — by a consistent margin, because VP8L's predictors and entropy coder are a generation ahead of DEFLATE's. Second, the lossy column is where the real damage is done: a photo as lossy WebP is an order of magnitude smaller than PNG. We ran through the equivalent JPG comparison in JPG vs PNG, and the web image formats guide maps where all three sit.
Where PNG still wins: everything that is not a browser
Every modern browser has rendered WebP for years. That sentence does a lot of work, because the moment you step outside a browser, WebP support gets patchy. Older Photoshop versions need a plugin. Some CMS upload forms and marketplace listing tools reject .webp outright. Desktop image viewers on older operating systems shrug at it. Office suites, print shops, and embedded systems lag even further behind.
PNG has none of these problems. It has been universally readable since the late 1990s — every image editor, every operating system, every office suite, every printer pipeline. When someone says a file "just works," they are usually describing PNG or JPG.
The workflow question
This is the part most comparisons skip. PNG is not just a delivery format; it is the default intermediate format. It opens everywhere, it never degrades on re-save, and every tool in every pipeline accepts it. That is why designers export working files as PNG even when the final asset ships as WebP.
The sane workflow looks like this: edit and archive in PNG (or a real working format like PSD), then export WebP for the website. WebP is the shipping container; PNG is the workshop. For the website-specific version of this decision, PNG vs WebP for websites goes deeper, and WebP vs JPG covers the photo side.
Which one when
| Job | Use | Why |
|---|---|---|
| Images on a website you control | WebP | smaller at equal quality, alpha included |
| Screenshots and UI graphics | WebP for shipping, PNG for sharing | size vs universal opening |
| Sending files to clients or print | PNG | opens everywhere, no questions asked |
| Editing and archiving | PNG | lossless, every tool reads it |
| Uploading to a form you do not control | PNG | many forms still reject WebP |
When you need to convert
If a WebP file bounced off an upload form or an old app, WebP to PNG converts it locally in your browser — transparency intact, nothing uploaded; the step-by-step is in how to convert WebP to PNG. Going the other way, PNG to WebP typically cuts a graphic's size by a quarter or more before it goes on a page. Both run entirely on your device.
The rule that falls out of everything above: keep your masters in PNG, ship WebP to the web, and convert on demand when the outside world disagrees.