Mobile versus desktop
Core Web Vitals measure three things: how fast the main content appears (LCP), how quickly the page responds to a tap (INP), and how much the layout shifts (CLS). Google uses them as a ranking signal. A site must pass all three to count as good.
| Item | Mobile | Desktop |
|---|---|---|
| All Core Web Vitals | 48% | 56% |
| LCP (loading) | 62% | 74% |
| INP (responsiveness) | 77% | 97% |
| CLS (visual stability) | 81% | 72% |
| TTFB (server response) | 44% | 55% |
Slow but steady progress
| Item | 2024 | 2025 |
|---|---|---|
| All Core Web Vitals | 43% | 48% |
| LCP | 59% | 62% |
| INP | 74% | 77% |
| CLS | 79% | 81% |
| TTFB | 42% | 44% |
Every metric improved, but slowly. Mobile Total Blocking Time went the other way. The median rose 58% to 1,916 milliseconds, a sign that pages are shipping more JavaScript.
The common, fixable mistakes
About 16 to 17% of mobile pages lazy-load their main (LCP) image. That delays exactly the image that should load first. 62% of mobile pages have at least one image without set dimensions, which causes layout shift. Only 17% of mobile pages with an LCP image use fetchpriority="high", although it takes one attribute to add.
My checklist for clients
- Never lazy-load the hero image. Add fetchpriority="high" to it.
- Set width and height on every image and embed.
- Serve WebP or AVIF images at the size they display.
- Remove unused plugins and scripts. Each one adds blocking time.
- Use good hosting with caching and a CDN. Only 44% of mobile sites have a good TTFB.
Frequently asked questions
What percentage of websites pass Core Web Vitals?
According to the 2025 Web Almanac, 48% of mobile sites and 56% of desktop sites have good Core Web Vitals.
Which Core Web Vital fails most often?
Largest Contentful Paint (LCP). Only 62% of mobile sites have a good LCP, compared with 77% for Interaction to Next Paint and 81% for Cumulative Layout Shift.
How do I improve LCP on my website?
Do not lazy-load the main image, add fetchpriority="high" to it, serve compressed WebP or AVIF images, reduce render-blocking scripts and use fast hosting with a CDN.
