What the numbers say
PNG stores the decoded pixels exactly, so it is much larger than a lossy WebP. In the table the photo grew from 403 KB to 3.37 MB, about 8.4 times larger. The screenshot went from 29 KB to 143 KB, and the illustration from 31 KB to 156 KB.
Converting does not bring back detail that the WebP already dropped. It gives you a lossless container for the pixels you have, which is useful in a few specific cases.
| Test image | WebP | PNG | Change | Time |
|---|---|---|---|---|
| Photo | 403 KB | 3.37 MB | 736% larger | 2.3 s |
| Screenshot | 29 KB | 143 KB | 392% larger | 986 ms |
| Illustration (alpha) | 31 KB | 156 KB | 409% larger | 1.7 s |
PNG stores the decoded pixels exactly, so it will be larger than a lossy WebP, most of all for photos. Converting does not bring back detail the WebP already dropped. Transparency is kept. Timings: one thread of WebAssembly on Node v22.23.4, Intel(R) Xeon(R) Processor @ 2.10GHz, 2 cores, measured 2026-10-31. Other devices will differ.
When PNG is the right target
- You are editing in software that cannot open WebP.
- You need transparency with hard, clean edges and a format that every tool reads.
- You want to avoid another lossy step in a chain of edits.
- A pixel-exact screenshot or interface graphic is going into a document.
If none of these fit, keep the WebP. A PNG made from a lossy WebP is a larger copy of the same picture, not a better one.
If size matters, pick something else
For photos, PNG is rarely the answer. Use WebP to JPG for a photo that has to open anywhere, or keep the WebP. For a graphic that must stay lossless, PNG is fine and the size growth is modest.
How the PNG is packed
After decoding, the tool runs the PNG through an optimiser, so the file is smaller than an unoptimised export. That costs time. The 2000 pixel photo took 2.3 s in the benchmark, against 986 ms for the screenshot. Transparency in the WebP is carried over.
Screenshots and interface graphics
Flat graphics are where PNG makes the most sense. The test screenshot came out at 143 KB, a small file with every edge exact. If PNG size is a problem for this kind of image, lossless WebP is often smaller. On the test screenshot it was 16 KB against 46 KB for the PNG, as the PNG to WebP page shows.
Large photos and memory
A big photo as a PNG is a big file. The test photo has about 2.7 megapixels and made a 3.37 MB PNG, so a 20 megapixel photo would land around seven times higher. The tool refuses images above 90 megapixels. On a phone, convert large photos one at a time.
Colour and metadata
The browser converts colours to sRGB while it decodes the WebP, so the PNG looks the way the WebP did. Metadata is removed by default. Open Advanced settings and look under Metadata if you want to keep the colour profile or the author line.
Questions
Will the PNG look better than the WebP?
No. It looks the same as the decoded WebP. PNG just does not lose any more detail.
Why is the PNG so big?
PNG is lossless. A photo has too much fine variation for lossless compression to shrink it much.
Does it keep transparency?
Yes.
Are animated WebP files supported?
Only the first frame is converted.