Lossy or lossless WebP for a PNG?
- Lossless reproduces the pixels of your PNG exactly. It suits screenshots, interface graphics, logos, diagrams and pixel art, where a changed pixel would show. It is typically smaller than the PNG.
- Lossy discards fine detail to get much smaller files. It suits photographs and soft illustrations that were saved as PNG. Transparency is kept, and the alpha channel is stored at full quality.
If you are unsure, convert a couple of files both ways and compare the sizes and the look. The list makes that quick.
What stays and what can change
- Transparency stays. Fully transparent and semi-transparent pixels both carry over.
- Hidden colour is not kept. The colour stored inside fully transparent pixels is not preserved. It is invisible, so the picture looks the same.
- Colours are converted to sRGB, and no colour profile is embedded.
- Metadata is removed by default. If your PNG has an EXIF block, Keep copies it into the WebP.
When to keep the PNG
A PNG that is already small, for example an icon with a handful of colours, can end up the same size or larger as WebP. If the list shows a file getting bigger, keep the PNG. Also keep PNG for programs that cannot open WebP. Going back is easy with WebP to PNG, and photos that do not need transparency are usually better as PNG to JPG.