What Is WebP? Compression, Transparency, and Compatibility

Two compression modes in one family

Lossy WebP predicts image blocks and stores differences, allowing an adjustable size-versus-detail tradeoff. Lossless WebP uses reversible transforms and entropy coding so decoded pixel values can be reconstructed.

This dual design lets WebP cover jobs historically split between JPG and PNG, although it does not guarantee a smaller result for every individual file.

• Lossy mode: suited to photographic content and final delivery.
• Lossless mode: suited to exact graphics, alpha, and repeated colors.
• Animated mode: stores timed frames in the WebP container.

Transparency and metadata

WebP can store an alpha channel, including with lossy RGB data. That makes it possible to compress photographic pixels while keeping transparent edges.

The extended container can also carry EXIF, XMP, and ICC chunks. A particular converter may omit those chunks when it draws pixels to a canvas and creates a new file, so format capability does not mean every export preserves metadata.

Browser support and non-browser workflows

Google's current WebP documentation lists native support in major browsers including Chrome, Safari, Firefox, Edge, and Opera. Browser support, however, is only one part of a workflow.

Desktop editors, email clients, office software, print systems, and upload portals can apply their own restrictions. Test the actual destination before deleting a JPG or PNG fallback.

• Web delivery: WebP is broadly usable in current browsers.
• Editing handoff: confirm the recipient's software.
• Restricted upload: keep a JPG or PNG derivative available.

When conversion helps—and when it does not

Converting a large PNG photo to lossy WebP can save substantial space. Converting an already compressed JPG to lossless WebP can instead preserve the JPG artifacts in a larger file.

Use the original source, match the mode to the image, and compare actual bytes and appearance. A format label alone is not an optimization result.

• Do not upscale during conversion unless dimensions must change.
• Do not assume lossless conversion restores quality.
• Retain a master outside the delivery pipeline.