WebP · Image formats
What is a WebP file?
WebP is an image format Google released in 2010 to make web pages smaller. It produces files roughly 25 to 35 per cent smaller than JPEG at the same visible quality, supports transparency the way PNG does, and can hold animation the way GIF does — one format covering all three jobs. Every current browser displays it, which is why so many websites now serve it and why "save image as" hands you a .webp file. The trouble starts after that: a lot of desktop software and most upload forms still do not accept it, so the format that makes the web fast becomes an obstacle the moment the image leaves the browser.
Where WebP came from and what it actually does
Google released WebP in 2010, built on compression techniques from the VP8 video codec. The goal was straightforward: images are the bulk of what a web page downloads, so making them smaller makes the whole web faster, and Google has a direct interest in a faster web.
The result replaces three formats at once. Lossy WebP competes with JPEG and wins by roughly a quarter to a third at equivalent quality. Lossless WebP competes with PNG and is typically around 25 per cent smaller. Animated WebP replaces GIF and is dramatically smaller — an animation that costs 2 MB as a GIF might be 200 KB as a WebP.
Browser support took years to arrive but is now universal across current browsers. That tipping point is why you started seeing .webp files everywhere at once.
Why you keep ending up with one
You did not choose it. Modern sites serve whichever format your browser says it can display, usually through a picture element or by content negotiation on the server. Your browser advertises WebP support, so the server sends WebP, and that is the file sitting in the browser cache.
When you then use "save image as", the browser writes out the file it actually received. There is no conversion step and no opportunity to ask for something else. The site was optimised for viewing, not for you keeping a copy.
This is exactly the same mechanism that produces AVIF files on newer sites, and it will keep happening as formats improve.
One extension, three different things
It is worth knowing that .webp does not tell you much on its own. A lossy WebP is JPEG-like: quality has been discarded and cannot be recovered. A lossless WebP is PNG-like: every pixel is exact. An animated WebP holds a sequence of frames.
That matters when converting. A lossless WebP converted to PNG loses nothing at all. A lossy one converted to PNG produces a large file that faithfully preserves compression artefacts already baked in — the PNG cannot restore what the WebP threw away. And an animated WebP converted to any still format gives you the first frame only, because PNG and JPG cannot hold a sequence.
What still cannot open it
Windows added WebP support to Photos and File Explorer, and macOS has supported it since Big Sur, so the operating systems themselves are mostly fine now. The gaps are in applications.
Older versions of Microsoft Office will not place a WebP into a document. Many desktop image editors, print services and photo kiosks refuse it. Most upload forms reject it, because their allowlists were written before WebP existed. And plenty of older phones and televisions cannot display it.
So the practical rule is: WebP is excellent for a website and awkward everywhere else.
When to keep it and when to convert
Keep it if the image is going onto a website you run. It is the right format for that job and converting to JPG would only make your page slower for no benefit.
Convert it if the image is going anywhere else — into a document, to a print service, into an upload form, or to another person. Convert to JPG for photographs and PNG when you need the transparency preserved. Either way you are trading file size for the near-certainty that it opens.
Frequently asked questions
What is a WebP file?
An image saved in a format Google released in 2010 to make web pages faster. It is roughly 25 to 35 per cent smaller than an equivalent JPEG and can also do transparency and animation.
Why did the website save my image as .webp?
Because that is the file the site actually sent your browser. Modern sites serve WebP to browsers that support it, and "save image as" writes out whatever was received.
Is WebP better than JPEG?
Technically yes, on file size at equivalent quality, plus it supports transparency and animation which JPEG cannot. JPEG wins on compatibility, and that is still the deciding factor whenever the image leaves the browser.
Will converting WebP to JPG lose quality?
A little, since both are lossy and the image is being re-encoded once. It is not visible on a normal photograph. Converting to PNG avoids any further loss but produces a much larger file and cannot recover detail the WebP already discarded.
Can I open a WebP without converting it?
Any current browser will display one — drag the file into a browser tab. Windows Photos and macOS Preview handle them too. The problem is usually a specific application or upload form rather than your computer.
What happens to an animated WebP when I convert it?
You get the first frame. PNG and JPG have no way to store a sequence, and browsers cannot write animated PNG, so the animation cannot be carried across.