What Is WebP? The Format Explained
The format behind half the 'why won't this open' moments online — smaller than JPG and PNG, supported by every browser, and rejected by plenty of desktop software.
WebP is a modern image format built by Google to make web pages lighter. It compresses photographs smaller than JPG and graphics smaller than PNG, it supports transparency, and it can be either lossy or lossless — one format covering jobs that used to need two. Every current browser displays it natively.
So why does it have a reputation as the file nothing will open? Because "every browser" is not "every program", and the moment a WebP leaves the browser it runs into software that was built around JPG and PNG and never caught up.
Why websites serve it
Images are usually the heaviest thing on a web page, and page weight is a ranking and user-experience factor. WebP typically produces files meaningfully smaller than an equivalent-quality JPG, and smaller than PNG for graphics — same picture, fewer bytes, faster page. From a site owner's point of view that's close to free, so a great deal of the web now ships images as WebP by default. When you right-click and save one, your browser hands you exactly what it was given.
Why your software won't open it
Plenty of desktop photo editors, older operating systems, print services, and upload forms predate WebP and simply reject it. The format that made the page load faster becomes the format your laptop won't touch. The fix is to convert it to something universal: WebP to JPG for photographs, or WebP to PNG if the image has a transparent background — JPG has no transparency, so converting a transparent WebP to JPG fills the background with solid white. Our guide on converting WebP when files won't open walks through it.
The part that surprises people: it does both lossy and lossless
Most formats pick a side. JPG is lossy, PNG is lossless — see our explainer on what that distinction means. WebP does both, and on this site it's the same control either way: PNG to WebP and JPG to WebP expose a quality slider, and pushed all the way to 1 the browser switches to lossless WebP — a pixel-identical copy, usually still smaller than the PNG it came from. Anywhere below 1 is lossy. That flexibility is exactly why one format can replace two.
It keeps transparency, too
WebP has a full alpha channel, like PNG — so a logo or cut-out stays transparent through the conversion. If you've been keeping heavy transparent PNGs around, WebP is usually the smaller way to store the same thing; our comparison of PNG vs WebP for transparency covers when to switch.
Should you convert your images to WebP?
If you run a website, yes — it's one of the cheapest page-speed wins available, and JPG to WebP and PNG to WebP handle a whole folder at once. If you're an everyday user just trying to open a file someone sent you, no — convert it out of WebP into JPG or PNG and move on. The right direction depends entirely on which side of the browser you're standing on.
FAQ
Is WebP better than JPG and PNG?
On file size, usually yes — for photos against JPG and for graphics against PNG. On compatibility, no: JPG and PNG open everywhere and WebP still doesn't. That trade is the whole story of the format.
Why did my download save as a WebP file?
Because the website served the image in WebP to load faster, and your browser saved exactly that. Convert it with WebP to JPG if your software won't open it.
Does converting to WebP lose quality?
Only if you want it to. Below quality 1 it's a lossy re-encode; at quality 1 it's lossless and pixel-identical. For most web use a lossy WebP is smaller and looks the same.