PNG to WebP Converter
- Writing the WebP discards picture detail to save space, and what it discards does not come back.
- The Exif data, the colour profile and anything else the original carried are not passed on: the picture is decoded to plain pixels and a new file is written from them.
- An animated PNG comes through as one picture — the image the format names as its default, or the first frame where it names none.
Needs JavaScript. Runs only here.
This page turns a PNG into a WebP on your own machine. Every conversion on this page runs in your browser. The picture is read, drawn and written on your own machine, and the file is not sent to a server.
Going the other way? Convert WebP back to PNG →
How do you convert a PNG to a WebP?
WebP keeps the alpha channel a PNG carries and usually needs fewer bytes for the same picture. What a browser will write from a canvas is the lossy mode.
- Choose the PNG file you want to convert. It is read inside this page, on your own machine.
- Set the quality between 0 and 1. A lower setting writes a smaller file and throws more detail away, and no two browsers read the number the same way.
- Select Convert to WebP. The page reads the first bytes of what came back and refuses the file if they are not WebP.
- Download the WebP. Nothing has been sent anywhere, so the file is ready as soon as it is written.
What Changes From PNG to WebP
PNG to WebP keeps the alpha channel either way. Lossless mode keeps every pixel and still usually saves space; lossy mode saves much more and discards detail to do it.
Each row below is one property of the picture: what it is in the PNG, what it becomes in the WebP, and whether it survives the trip. Convert a file and the same rows fill in with the measurements from your own picture.
| Property | In the PNG | In the WebP | Verdict |
|---|---|---|---|
| Dimensions | as the file has them | as the file has them | kept |
| Colour model and bit depth | RGB with alpha, 8 bits per channel | RGB with alpha, 8 bits per channel — 8 bits per sample, whatever the source held | kept |
| Alpha channel | present | carried through unchanged | kept |
| Colours used | up to 16,777,216 | the same pixels | kept |
| Animation frames | 1, or several — PNG can carry an animation | 1 — the format’s default image, or the first frame where it names none | changed |
| Metadata (Exif, ICC) | present in the file | dropped — a new file is written from pixels | lost |
| Compression | lossless, deflate | lossy, in a VP8 chunk | changed |
| File size | the file you chose | smaller | changed |
the pixels survive; some of the detail and the Exif data do not.
Going Back to PNG
Converting back does not restore what this step dropped, so convert the WebP result back to PNG only when you need a PNG file.
The change above runs one way — go back from WebP to PNG writes a new file, not the original.
What Travels With the Picture
What the two formats are, and what the browser does with a picture on the way between them. None of this depends on which PNG you bring.
How PNG and WebP Are Defined
| Property | PNG | WebP |
|---|---|---|
| Compression | lossless - deflate with a sliding window of at most 32768 bytes (compression method 0) | two modes in one container: lossy in a VP8 chunk, lossless in a VP8L chunk |
| Alpha channel | yes - a full alpha channel on colour types 4 and 6; a tRNS chunk gives a transparent colour key on types 0 and 2 and per-entry alpha on type 3 | yes, in both modes - a lossy file carries its alpha in a separate ALPH chunk, and a lossless file carries it inside the VP8L chunk |
| Animation | yes - APNG is normative in the Third Edition, using the acTL, fcTL and fdAT chunks | yes - controlled by the ANIM and ANMF chunks in the extended file format |
| In one sentence | PNG stores a picture without losing anything: the specification defines lossless as reconstructing the original data exactly, bit for bit. It carries an alpha channel, and since the Third Edition it can carry frame-based animation as well. | WebP has two modes in one container. Lossy WebP throws detail away the way JPEG does; lossless WebP keeps every pixel. Either mode can carry transparency, and the container can also hold an animation. |
- A PNG file begins 89 50 4E 47 0D 0A 1A 0A.
- A WebP file begins 52 49 46 46 ("RIFF"), then a four-byte size, then 57 45 42 50 ("WEBP").
- PNG is defined by PNG Specification (Third Edition), W3C Recommendation 24 June 2025; the Second Edition is ISO/IEC 15948:2004. The Third Edition is not itself an International Standard..
- WebP is defined by WebP Container Specification (Google); the bitstreams are RFC 6386 (lossy) and the WebP Lossless Bitstream Specification.
JPEG and lossy WebP save space by discarding picture detail, and what they discard does not come back. PNG, BMP and lossless WebP keep every pixel they are given, and GIF keeps every pixel it is left with after the palette has been applied.
PNG, GIF, WebP and ICO can carry transparency; JPEG cannot, because the standard defines no alpha channel, and a bitmap written here is opaque. Converting to a format without transparency fills the clear areas with a background colour.
PNG allows bit depths of 1, 2, 4, 8 and 16, and five colour types: greyscale, truecolour, indexed-colour, and each of greyscale and truecolour with alpha. Not every depth is legal for every type.
WebP has a lossy mode and a lossless mode, and both can carry transparency. Lossy WebP discards detail the way JPEG does; lossless WebP keeps every pixel.
Converting a picture back to the format it came from does not return the original file. Whatever a step discarded stays discarded, and the return trip writes a third file.
The browser decodes the picture to plain pixels and writes a new file from them, so the Exif data, the colour profile and anything else the original carried are not passed on.
Whether a browser can be asked for lossless WebP from a canvas is not settled. The specification gives only a quality number for formats with variable quality and names no lossless option, and Safari does not write WebP from a canvas at all.
The only formats browsers are documented as writing from a canvas are PNG, JPEG and WebP. Safari does not write WebP from a canvas at all. GIF, BMP and ICO appear nowhere in the compatibility data.
A canvas holds pixels and nothing else, so a file written from one carries no Exif data, no thumbnail and none of the original file's other metadata. The canvas specification never mentions Exif; this follows from writing the file out of a bitmap.
Lossless or Lossy WebP?
What this page can write
The lossy mode, when the browser has an encoder for it. Whether a browser can be asked for lossless WebP from a canvas is not settled. The specification gives only a quality number for formats with variable quality and names no lossless option, and Safari does not write WebP from a canvas at all.
What the two modes differ on
WebP has a lossy mode and a lossless mode, and both can carry transparency. Lossy WebP discards detail the way JPEG does; lossless WebP keeps every pixel.
What is the same either way
The transparency. WebP carries an alpha channel in both modes, so a clear background comes through whichever one wrote the file, and nothing is laid onto a colour.
Common Mistakes
- Asking this page for a lossless WebP. A canvas offers a quality number and names no lossless option, so the page refuses rather than mislabelling a file.
- Assuming every browser writes a WebP. This page asks before it offers the button.
- Quoting a saving. The bytes depend on the picture, so the transfer table measures yours.
Frequently Asked Questions
How much smaller is the WebP than the PNG?
It depends on the picture, so this page prints both sizes after you convert one rather than quoting a figure that would be wrong for the next file.
Should you choose lossless or lossy WebP?
Lossless for line art, screenshots and anything with sharp text; lossy for photographs, where the saving is large and the loss is hard to see.
Does WebP keep the PNG's transparent areas?
Yes. WebP carries an alpha channel in both of its modes, so a clear background stays clear and a soft edge stays soft.
Can lossless WebP be produced in the browser?
Not from a canvas, on the evidence available. Whether a browser can be asked for lossless WebP from a canvas is not settled. The specification gives only a quality number for formats with variable quality and names no lossless option, and Safari does not write WebP from a canvas at all.
You can, but the round trip is not the file you started from: the WebP to PNG direction.
Related Conversions
The rest of the family sits on the full image format grid.