Lossless output from a possibly lossy source
WebP comes in two flavours: lossy (VP8, with an optional alpha plane) and lossless (VP8L). When you convert to PNG here, the browser decodes either kind into 8-bit RGBA pixels, draws them on a canvas the same size as the original, and encodes that canvas as PNG. Nothing is flattened, so transparent and semi-transparent pixels are kept exactly as decoded. No quality slider is shown because PNG does not need one.
The key thing to understand is that PNG preserves what the decoder produced, not what the artist originally drew. If the WebP was lossy, any blur or ringing it already contains is now stored permanently, just without adding more.
Worked example
A 512×512 sticker exported as a lossy WebP with transparency is 18 KB. Converted here, the PNG holds the same 262,144 pixels, and the cut-out stays see-through. Because a PNG of a detailed illustration is usually several times larger than a lossy WebP, expect something like 80 to 200 KB. A 1920×1080 photographic WebP of 150 KB can balloon to 2 to 4 MB as a PNG. Neither figure means quality improved. These are rough estimates and vary by content.
When this conversion makes sense
| Goal | Is PNG the right target? |
|---|---|
| Edit a downloaded sticker or logo in an older editor | Yes, alpha is kept |
| Upload to a site that rejects WebP, with transparency needed | Yes |
| Send a photo by email | No, use WebP to JPG for a smaller file |
| Keep an animation | No, only the first frame is exported |
Edge cases
- Animated WebP. The browser provides one frame to the canvas, so the PNG is a still. Animated PNG (APNG) output is not supported by this page.
- Browser must decode the file. WebP has been displayable in Safari since version 14 (2020). A very old browser may report that the image could not be converted.
- Metadata and colour profiles. EXIF and embedded ICC data are not written into the PNG. Colours are whatever the browser canvas renders, usually sRGB.
- File name. The download keeps your source name and swaps the extension, so
sunset.webpbecomessunset.png.
Going the other way for web use? Image to WebP turns a PNG into a much smaller WebP, and AVIF to PNG handles the newer format.