Convert PNG to WEBP
Convert a PNG to WEBP, lossy or lossless.
How it works
WEBP is a raster format from Google that replaces both PNG and JPEG. For photographic content its lossy mode typically produces files 25–35% smaller than a JPEG of comparable quality; for flat graphics and screenshots its lossless mode usually beats PNG by 20–30%. Unlike JPEG it supports an alpha channel, so a transparent PNG stays transparent.
Lossy or lossless for PNG
The quality slider only applies to lossy mode. It is not a percentage of anything: it is a knob on the encoder's rate-distortion tradeoff, where 75 is a common default and anything above about 90 spends a lot of bytes for changes you cannot see.
Lossless mode ignores the slider entirely and reproduces the source pixel for pixel, which is the right choice for logos, diagrams, screenshots and any image with hard edges or large flat areas.
Browser support and local encoding
Every browser released since 2020 displays WEBP, including Safari from version 14. The remaining reason to keep a PNG is a tool further down your pipeline that cannot read it. Some older desktop software and a few print workflows still cannot.
This converter decodes and re-encodes using WebAssembly builds of libpng and libwebp running inside a Web Worker on your machine. Nothing is uploaded, so there is no queue, no size cap beyond your device's memory, and no daily limit to hit.
Questions
Is my image uploaded to a server?
No. Open your browser's developer tools, switch to the Network tab, and convert a file. You will see no upload request. This is the difference between this tool and most of the alternatives, several of which POST your image to a server to perform a conversion the browser can do by itself.
Does transparency survive the conversion?
Yes. WEBP has a full 8-bit alpha channel in both lossy and lossless mode, so transparent regions are preserved.
Why is my lossless WEBP larger than the PNG?
It happens with images that are already well-compressed by PNG's filtering: very small images, or images with few colours that PNG stores as an indexed palette. When it does, keep the PNG. The result panel shows the byte delta so you can see it before downloading.
Is there a file size limit?
No imposed limit. The practical ceiling is your device's memory, which is roughly a 250 MB working set on a phone and several gigabytes on a desktop. Very large images are refused up front with an explanation rather than crashing the tab.