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WebP
What is a WebP file?
Google format for the web. Roughly 30% smaller than JPG at the same quality, with transparency.
What WebP is
WebP is a binary format, meaningful only to a program that knows it. It stores a grid of pixels, so enlarging it past its own resolution softens it. It is used for the web and handing a finished file over.
The extension is .webp, and the full name is WebP Image. Both matter less than what the file can hold, which is what the rest of this page is about.
Where WebP came from
Google published it in 2010. The specification is RFC 9649.
Age is worth knowing here for one practical reason: the older a format is, the more programs have had time to learn it.
The specification is public
Anyone can implement it without asking permission or paying a licence, which is why it turns up in so many programs and why files written twenty years ago still open.
Nothing is thrown away
WebP stores its content exactly. Saving it again changes nothing, so it can be opened, edited and re-saved as often as you like without accumulating damage — which is what makes it a working format rather than a delivery one.
It can be transparent
WebP carries an alpha channel, so a logo keeps its soft edges over whatever sits behind it instead of arriving in a white box.
It can hold more than one frame
WebP can store an animation rather than a single still. That is worth knowing before converting one: a target that holds one frame keeps the first and drops the rest, usually without saying so.
Colour it can describe
Up to 8 bits per channel. It can work in RGB and YCbCr, the model video and JPEG compress in.
Eight bits per channel is what a screen shows and what nearly every delivery format carries.
There is a size limit worth knowing
WebP cannot describe an image larger than 16,383 pixels on a side. That is far beyond an ordinary photograph and well within reach of a stitched panorama or a high-resolution scan, which is exactly when people meet it.
What opens WebP
Adobe Photoshop, GIMP and Squoosh read it, and so do most programs of the same kind.
If a file will not open, the format is rarely the problem — it is more often that the program predates it. Converting to something older is the reliable way past that, and it is what the rest of this site is for.
Opening it in a browser
Every current browser reads it.
That makes it a safe thing to put on a page or attach to a message without wondering what the other end has installed.
What it can carry besides the content
WebP can hold EXIF, XMP and ICC profiles.
Whether any of it survives a conversion depends entirely on the target, and the honest answer is usually "some of it".
It is a delivery format
WebP is meant to be handed over rather than worked in. Editing one is possible and rarely pleasant; the sane approach is to change the source and export again.
The facts, in one place
| Extension | .webp |
|---|---|
| Media type | image/webp |
| Published by | |
| First published | 2010 |
| Specification | RFC 9649 |
Converting WebP to something else
Converting something else to WebP
Formats worth considering instead of WebP
Where these figures come from
The claims on this page are checkable, and these are the documents that settle them.