Convert PNG to WebP
Convert PNG images to WebP in your browser with transparency intact. Logos and screenshots get much smaller without the white box JPEG leaves behind.
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How it works
The PNG is decoded to pixels, drawn onto an OffscreenCanvas with no background fill, and encoded as WebP by the browser's own libwebp build. Skipping the fill is the entire point: the canvas keeps its alpha channel, WebP has a real one to write it into, and a transparent logo comes out still transparent. Every step happens inside a Web Worker on your machine.
Measured results
These figures come from running this exact tool over a fixed set of sample files on every build, not from an estimate.
| Sample file | Settings | Before | After | Change |
|---|---|---|---|---|
| logo-transparent.png | quality 82 | 19 KB | 7 KB | −62% |
| photo-gradient.png | quality 82 | 3.36 MB | 284 KB | −92% |
| screenshot-text.png | quality 82 | 219 KB | 66 KB | −70% |
Benchmark run 2026-08-01.
What to watch out for
Lossy compression works on colour, and the colour underneath a fully transparent pixel is undefined. Some encoders leave rubbish there that reappears as a coloured halo when the image is later composited onto a dark background. Check a logo against black before shipping it.
WebP has a separate lossless mode, VP8L, that often beats PNG outright on flat graphics. Through the canvas only the lossy path is reachable, and quality 100 is not the same thing. For a logo that must stay pixel-exact, keep the PNG or optimise it instead.
The WebP container stores width and height in fourteen bits, so a panorama or a tall stitched screenshot wider or taller than 16383 pixels cannot be encoded at all. PNG has no such ceiling, which is why an oversized image fails here and not on the way in.
Limits
Files up to about 50 MB work reliably. Beyond that, the ceiling is your device's memory rather than any rule we impose — the work happens on your own machine. Tested in Chrome 140, Firefox 143, Safari 18.
The transparency argument
Converting a PNG to JPEG forces a decision nobody wants to make: transparency has to become some solid colour, and whichever colour you pick is wrong on some background. WebP removes the dilemma entirely, because it stores an alpha channel the same way PNG does. A logo converted here still floats.
That makes this the sensible destination for exactly the files PNG is normally used for — logos, icons, UI screenshots, anything with a cut-out edge — while still cutting the file size substantially.
Where the savings come from
A PNG is lossless. It reproduces every pixel exactly, and for photographic content that fidelity is enormously expensive: a screenshot of a photo can easily be five times larger as PNG than as WebP with no visible difference.
For flat graphics the gap is smaller but still real. PNG compresses each row by predicting it from the row above, which handles large areas of identical colour very well. WebP predicts in two dimensions from neighbouring blocks, which handles gradients, soft shadows and antialiased edges better than PNG’s row-wise approach ever could.
When to keep the PNG instead
Three cases, and they are worth naming plainly.
If the image must survive further editing, stay lossless — each lossy save compounds. If it is a diagram or logo destined for print rather than a screen, the size saving is irrelevant and the fidelity is not. And if you need an image that opens in software older than about 2018, PNG remains the safer choice; WebP support is universal in browsers but still patchy in desktop applications.
Everything here runs in your own browser, so trying the conversion and comparing the two files costs nothing. Nothing is uploaded, and the original on your disk is never touched.
Your files never leave your browser. Last updated 2026-08-01.
Next step
Your file is already here in this browser, so the next tool starts with it loaded.
Related tools
- Convert PNG to JPGConvert PNG images to JPG in your browser. Pick the quality and the colour that replaces transparency. Files are never uploaded and nothing is stored.
- Convert WebP to PNGConvert WebP images to PNG in your browser, keeping transparency. Expect the file to grow — PNG stores every pixel exactly, artefacts included.