Key takeaways
- Core Web Vitals measure loading (LCP), responsiveness (INP) and visual stability (CLS).
- Google’s ‘good’ thresholds are 2.5 seconds, 200 milliseconds and 0.1, measured on real visits.
- They’re one ranking signal among many, but fast, stable pages also lose fewer visitors before they enquire.
What does each one measure?
| Metric | Measures | Google’s “good” threshold |
|---|---|---|
| LCP | How long the main content takes to appear | 2.5 seconds or less |
| INP | How quickly the page responds to taps and clicks | 200 milliseconds or less |
| CLS | How much the layout jumps while loading | 0.1 or less |
Google judges each metric at the 75th percentile of real visits, so most of your visitors, not just the ones on fast connections, need a good experience. INP replaced the older FID metric in 2024.
What does LCP look like in practice?
LCP is the moment the biggest thing on the screen appears: usually the hero image or the main heading. On a phone over mobile data, a large uncompressed photo, slow hosting or a pile of scripts loading first can push it well past 2.5 seconds. The visitor sees a blank or half-built page and often leaves.
What does INP look like in practice?
INP is how long the page takes to react when someone taps a button, opens a menu or types into a form. Heavy JavaScript, chat widgets, tracking scripts and complicated page builders are the usual causes of slow responses. The visitor taps, nothing happens, and they tap again.
What does CLS look like in practice?
CLS is the jump when an image, banner or ad loads late and pushes everything down, often just as someone goes to tap a link. Images without fixed sizes, cookie banners that push content, and fonts that swap late are the common causes.
How do you check your site?
The Core Web Vitals report in Search Console shows real visitor data grouped by similar pages, so you can see which templates have problems. PageSpeed Insights shows real data for a single page plus a lab test with suggestions, and Lighthouse in Chrome runs the lab test on demand. Real-visitor data is what Google counts.
What usually fixes poor scores?
- Modern image formats such as WebP or AVIF, sized for the screen, with width and height set.
- Less JavaScript: fewer plugins, widgets and tracking tags, and nothing loaded that the page doesn’t use.
- Fonts that load without shifting text.
- Good hosting and caching, ideally with a CDN close to your visitors in the region.
- Removing page builders or themes that add far more code than the page needs.
Do they matter for rankings?
They’re one signal among many, and relevant, helpful content still matters most. A slow page with the best answer can outrank a fast page with a weak one. But speed affects every visitor, and slow pages lose people before they ever read your offer, so it’s worth fixing on its own.
How fast is this site?
This website is built as static HTML with very little JavaScript, using Astro with a headless CMS, and we test each page template with Lighthouse on mobile before release. It is the same approach we use for client sites where speed matters, described on our website design and development page.