Website performance is a feature now. Users don't bounce because they read your "we take performance seriously" copy — they bounce because the page took 4 seconds to draw. Images are the heaviest thing on most pages, and that's where the biggest, easiest wins still live in 2025.
What WebP actually is
WebP is an image format from Google, designed specifically for the web. It supports both lossless and lossy compression in the same container, plus animation and full alpha-channel transparency. In other words, it does everything PNG does, everything GIF does, and most of what JPEG does — usually in a smaller file.
The three things WebP buys you
1. Dramatically smaller files
WebP's lossless mode beats PNG by ~26% on average. WebP's lossy mode beats JPEG by ~25–34%. For a media-heavy site, that's the difference between a 6 MB landing page and a 2 MB one — and that delta hits every visitor on every load.
2. A direct boost to Core Web Vitals
Google measures how fast your largest piece of content paints (LCP) and uses it as a ranking signal. Hero images are usually the LCP element. Smaller hero image → faster LCP → better signal. There aren't many ranking levers that take an afternoon to pull and move the needle.
3. Versatility you don't have to think about
- Lossless or lossy — pick per image, not per format.
- Transparent backgrounds work the way they do in PNG.
- Animation ships in WebP at a fraction of an animated GIF's size.
"But what about old browsers?"
WebP is supported by >97% of global browsers. The remaining few are mostly very old in-app browsers and abandonware. The standard answer is to ship WebP with a PNG fallback via the <picture> element — see the browser support guide for a paste-ready snippet.
Roll it out without drama
- Identify your top 20 image URLs by traffic.
- Convert with our in-browser converter at quality 80 (good default).
- Either swap the file extension everywhere, or wrap with
<picture>. - Re-run Lighthouse and watch LCP drop.
If you want a longer technical rationale, our PNG vs WebP deep dive covers the codecs in depth. If you want numbers, see the page speed tests.