PNG to WebP converter

Convert PNG images to WebP for free, right in your browser — no sign-up, no upload.

PNG to WebP keeps transparency and usually shrinks the file, but which kind of WebP you write matters. At the default quality 92 the WebP is lossy: the 512 × 512 photo went from 791,555 to 59,824 bytes. At quality 100 Chromium writes lossless WebP, pixel-identical to the PNG — 379,076 bytes for that photo. For pixel art lossy WebP is the wrong choice: on a Kenney sprite sheet it changed half the pixels and came out at 8,692 bytes, against 2,814 lossless and 1,996 for the original optimised PNG.

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Making a game?

Nerulio is a 2D game asset studio first: draw pixel art, cut sprite sheets into animations, pack texture atlases, check autotile tilesets and export them for Godot, Unity, Phaser and other engines. It runs in your browser; files stay on your device.

Open the game studio →All game tools Sprite sheet slicer Pixel art editor Normal and texture maps

Two different encoders behind one extension

Lossy WebP is based on the VP8 video codec and stores colour at half resolution (Y′CbCr 4:2:0). Lossless WebP stores exact ARGB and compresses by predicting pixels and reusing repeated data. Both keep an alpha channel, so a transparent PNG stays transparent either way.

The browser chooses the encoder from the quality it is given. In Chromium 153 quality 100 produced lossless files — every pixel identical — and anything lower produced lossy ones. The slider starts at 92, so move it to 100 for UI, text and pixel art.

Lossy WebP damages hard pixel edges in the colour channels: on the Kenney sheet the largest error was 108 of 255 while alpha stayed exact. JPG would be worse still for such a file, because it drops alpha altogether.

Lossy WebP: VP8-based, colour at half resolution; small files for photos.
Lossless WebP: Exact ARGB pixels; written by Chromium at quality 100.
Chroma subsampling 4:2:0: Colour stored for every 2 × 2 block instead of every pixel; smears single-pixel colour details.

A photo and a sprite sheet as WebP (measured)

Nerulio's converter code, Chromium 153, 2026-09-28.

Photo: astronaut.png   512 x 512    791,555 bytes
  WebP q92  (lossy)      59,824 bytes   SSIM 0.9883
  WebP q100 (lossless)  379,076 bytes   identical pixels

Pixel art: Kenney characters   224 x 74    1,996 bytes
  WebP q92  (lossy)       8,692 bytes   8,481 pixels changed, max error 108/255
  WebP q100 (lossless)    2,814 bytes   identical pixels

Soft edges are the one small exception at quality 100: on a Kenney UI button, 26 of 12,288 pixels differed by at most 4/255 (the button has 38 semi-transparent edge pixels, where browsers round premultiplied alpha); everything else matched exactly.

What the WebP keeps

In the PNG	What the converter does	In the WebP
RGB pixels	Quality below 100: lossy VP8; 100: lossless (Chromium)	Approximate or identical pixels
Alpha channel	Kept	Alpha kept (exact in both measurements)
Colour profile	Pixels drawn in the browser's sRGB canvas	`ICCP` chunk with sRGB written by Chromium
Text chunks, EXIF	Not copied	None
APNG animation	Rejected	—

Check the result

Put the WebP on a dark and on a light background: the transparency should look the same as the PNG's.
For graphics, zoom to 400 % on a sharp edge. Coloured smudges mean the file is lossy; convert again at quality 100.
Make sure the destination accepts WebP: current browsers do, some upload forms and older apps do not.

Troubleshooting

Symptom	Likely cause	How to check	Fix
Pixel art looks soft or has coloured specks	The default quality 92 wrote lossy WebP	Zoom in on one-pixel details	Set quality to 100 under Advanced and convert again (lossless in Chromium)
The WebP is bigger than the PNG	A small, already optimised PNG (indexed colours) that lossless WebP could not beat	Compare: 1,996-byte PNG vs 2,814-byte WebP on the Kenney sheet	Keep the PNG
The upload form rejects .webp	The site accepts JPG and PNG only	Read its list of accepted formats	Keep the PNG, or use PNG to JPG for photos
"Lossless" WebP differs in another browser	Only Chromium was measured; another browser may treat quality 100 differently	Compare the pixels with the PNG in an editor	Use PNG where exact pixels are required

Other ways to do it

Option	When it is the better choice
Keep the PNG	Pixel art and icons already optimised as PNG — the Kenney sheet stayed smallest as PNG.
Compress with Auto	You want the smallest file that stays above a similarity floor, whatever the format.
WebP to PNG later	You only need WebP for the web copy: keep the PNG master and convert back if a tool needs PNG.

What this page does not cover

The switch to lossless at quality 100 was measured in Chromium 153 only.
Text chunks and EXIF are not copied; animated PNG is refused.

Versions and sources

Measured on 2026-09-28 in Playwright Chromium 153 with Nerulio's converter path, on the astronaut fixture and two Kenney CC0 files (pixel-platformer-characters.png, kenney-blue-button.png). WebP's lossy and lossless modes and its 4:2:0 colour are described by MDN.

Official documentation used

MDN: Image file type and format guide

PNG to WebP converter

PNG is lossless and supports transparency — ideal for logos, screenshots and graphics, but large for photos.

WebP is a web format that is usually smaller than JPG or PNG at similar quality and also supports transparency.

Your file is never uploaded — it is processed inside this browser.

Example

Example generated with this tool. ZIP tools show their preview; inspect the downloaded archive for every file.

Convert image

Export PNG, JPG or WebP. JPG flattens transparency.

How it works

Open an image
Select PNG, JPG or WebP
Convert and download the new file

Supported formats

PNG / JPG / WebP / AVIF / HEIC → PNG / JPG / WebP — Input decoding and output encoding depend on browser support. Animated inputs are rejected; select a still frame first.

What this tool does

Re-encodes the image into the selected format rather than renaming its extension.

Implementation and verified quality

advanced · browser image codecs. Quality qualification is in progress. Pro/Flagship quality has not been established.

Before you export

JPG has no transparency. Canvas export does not promise preservation of metadata, color profiles or animation.

Frequently asked questions

Which format keeps a transparent background?

Choose PNG or WebP. JPG flattens transparency onto the selected background color.

Are my files uploaded?

This tool processes the files you open on your device without uploading them. Images you explicitly attach to community posts are uploaded separately. Optional engines and models are downloaded from third parties; those requests expose connection information such as your IP address.

Will my work be saved automatically?

No. Images and editing state stay in this tab; media output can use local temporary storage. Changing language preserves your work; reloading, closing the tab, or following a link to another page can clear it.