PNG to WebP
Your images never leave this device
WebP gives you a PNG’s transparency at something closer to a JPG’s file size. It carries a full eight-bit alpha channel, so a cut-out stays a cut-out, and it compresses the picture itself lossily, which is where the saving comes from. A transparent graphic that was 800 KB routinely lands nearer 150.
How to convert PNG to WebP
The white background this site’s other converters paint behind a transparent image is not painted here, and that is not a detail. Flattening happens only when the output format has nowhere to put an alpha channel. WebP has one, so transparent pixels are encoded as transparent, and a logo dropped onto a coloured page still sits on that colour.
WebP is really two formats wearing one extension. Lossless WebP competes with PNG, and Google’s own measurement has it compressing 42 per cent better than libpng’s default output and 23 per cent better than an aggressively optimised ZopfliPNG. Lossy WebP competes with JPEG, and that is where the larger savings are; this page writes lossy WebP, with the quality slider running from 40 to 100. On a small icon with three flat colours the difference between the two modes barely registers. On an illustration with soft gradients and a transparent border it is enormous.
One hard ceiling is worth knowing before you feed it a poster. Lossy WebP stores its width and height in fourteen bits, which caps either dimension at 16,383 pixels. A stitched panorama or a scanned architectural drawing can exceed that, and no quality setting helps; those have to stay PNG or be resized first.
Keep the PNG when it is a working file you will edit again, when the destination is desktop software more than a few years old, or when the image is small and flat enough that both formats have already reached the floor of what compression can do.
What people use it for
- Cutting page weight without losing a transparent background
- Bringing Largest Contentful Paint down on a page carrying a big illustration
- Replacing PNG product cut-outs on a shop with something a quarter of the size
- Preparing icons and diagrams for a static site build
- Shrinking a PNG that a lossless compressor had already run out of room on
Questions
Yes, a full eight-bit alpha channel, exactly like PNG. This tool paints no background behind it, so a cut-out stays a cut-out.
All current ones. Safari added it in version 14, in 2020, which was the last real gap.
The format can be either. This page writes the lossy kind, which is where the size saving comes from. At quality 85 it is visually indistinguishable for most images.
Small images and flat two-colour graphics are already near the floor of what any format can manage. The gains are biggest on photographs and detailed artwork.
Yes. Lossy WebP records its dimensions in fourteen bits, so neither side can exceed 16,383 pixels. Resize a larger image first, or leave it as a PNG.
Recent versions of both, yes. Older ones cannot, which is the case for keeping a PNG or JPG copy for desktop work.
The format does. This converter writes a single frame, because it is built around still images.
It is dropped. The file is written from a canvas, so no EXIF, no colour profile and no text chunks come across.
Yes if it is a source file you will edit again. A lossy WebP is a delivery format, not a master.