WebP vs JPG: Is WebP Actually Better for Websites?
Short answer
For images on a website, yes — Google's own study puts WebP 25–34% smaller than JPEG at matched visual quality, and every current browser supports it. Outside the browser it is a liability: many desktop applications, print services and older devices cannot open it.
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The size advantage is real but not universal
WebP's lossy mode uses more modern compression than JPEG's. The figure everyone quotes comes from Google's own 2010s study, which found WebP files 25–34% smaller at matched SSIM across four photographic corpora — including about 11,000 crawled images filtered to photograph-like content.
Two things about that number are worth knowing before you rely on it. It is measured **at matched visual quality**, not at the same quality number — q75 in one encoder does not mean q75 in another, so setting both to 75 and comparing sizes measures something else. And the corpus was photographs, which is the content WebP was tuned for.
Our own measurements on non-photographic content land well outside that range in both directions. On a smooth gradient WebP was 65% smaller than JPEG at quality 75, and on flat colour blocks 67% smaller — far better than the published figure. On pure noise it was 1% *larger*. The published range is sound for photographs; it is not a general law, and content is what decides.
It is not universal. For simple graphics with few colours, a well-optimised PNG can still be smaller than lossless WebP. This page previously said the gap narrows at high quality settings; measuring it, that turned out to depend entirely on content — on a smooth gradient WebP's advantage over JPEG grew from 42% at quality 50 to 71% at quality 95, while on noise it shrank from 32% behind to level. The honest summary is that WebP usually wins, by an amount the content decides.
What WebP can do that JPG cannot
Transparency is the big one. WebP supports a full alpha channel, so it can replace PNG for graphics as well as JPEG for photos — one format covering both roles.
It also supports animation, which makes it a far better choice than GIF for short loops: comparable animation at a small fraction of the file size, with full colour instead of GIF's 256.
| WebP | JPG | |
|---|---|---|
| Typical size (photo) | 25–34% smaller at matched quality | Baseline |
| Transparency | Yes | No |
| Animation | Yes | No |
| Browser support | All current browsers | Universal |
| Desktop apps | Patchy | Universal |
| Print services | Often rejected | Universal |
| Encoding speed | Slower | Very fast |
When not to use WebP
Anything that leaves the browser. If a user will download the image and open it in desktop software, email it to a colleague, or send it to a print shop, WebP creates friction that a smaller file does not justify.
The practical pattern most sites use is to serve WebP through the picture element with a JPG fallback, so browsers get the small file and everything else still works.
- Website images → WebP, ideally with a JPG fallback
- Downloads users will open elsewhere → JPG
- Short animations → WebP or MP4, not GIF
- Print or professional workflows → JPG or TIFF