What is a WebP file and how do you open it?

WebP is an image format developed by Google for the web. It can compress with loss, like JPG, or without loss, like PNG, and either way it can keep a transparent background. Google's own figures put lossy WebP files 25–34% smaller than comparable JPGs, and lossless ones 26% smaller than PNGs.

Our own test agrees: 17 high-quality phone-sized photos saved as WebP at High (85) quality came out at half the size of the original JPGs, with no difference we could see at normal viewing size. Smaller images mean faster pages, which is why most large websites now serve WebP.

When you save an image from a website, you get the file the site actually sent, and more and more sites send WebP. Image services and content delivery networks often convert pictures to WebP automatically for browsers that support it, so the same picture can download as a JPG on one device and as a WebP on another. The file is not damaged or unusual; it is just more efficient.

Every current browser displays WebP, and recent versions of Windows, macOS, iOS and Android show it in their built-in photo viewers. Older image editors and Office versions, many print services, some messaging and social apps, and plenty of upload forms on official websites still reject it. That is when converting helps.

Converting makes the file bigger, because JPG and PNG are less efficient than WebP. We converted our 17 WebP photos back: as JPGs they were 2.2 times larger on average, as PNGs ten times larger.

The picture itself does not get worse in any way you would notice: the JPG is saved at quality 92 by default, high enough to add no visible loss. It does not get better either: whatever detail the WebP left out stays out. If you have the original JPG or PNG the WebP was made from, use that instead.

Choose JPG for photos: the files are much smaller than PNG, as the table shows. Choose PNG for logos, icons, screenshots and anything with transparency: edges stay sharp and the background stays transparent. If you convert a transparent WebP to JPG, the transparent areas become white, because JPG cannot store transparency.

Keep the WebP versions on your site: they load faster for every visitor. Convert to JPG or PNG only the copies you need to send, print or upload elsewhere. Going the other way, from JPG to WebP, is covered in our guide to making website images lighter.

The 17 photos are the Unsplash photographs that ship with Edubuntu, scaled to 4,032 pixels on the long side and saved as JPG at quality 92. We converted them to WebP at High (85) and back to JPG and PNG with this site's converters, which run the same code and ImageMagick version as our servers. Sizes depend on the picture, so treat the numbers as typical rather than exact.