Core Web Vitals checker with fixes in plain English

What are Core Web Vitals?

Core Web Vitals are three Google metrics for real-world page experience: Largest Contentful Paint (loading), Interaction to Next Paint (responsiveness) and Cumulative Layout Shift (visual stability). A page passes when at least 75% of visits are “good” for each one: LCP of 2.5 seconds or less, INP of 200 milliseconds or less and CLS of 0.1 or less. They are part of Google’s page experience signals. They won’t outrank better content, but on competitive queries and on slow mobile networks, common across South Asia, speed decides who keeps the visitor.

How to use the checker

1. Enter a URL and choose Mobile (Google indexes the mobile version) or Desktop.
2. Wait 20–60 seconds while Google’s PageSpeed Insights runs. Results are cached for 12 hours, so re-checks are instant.
3. Start with the Real users section: that is the data Google uses. The lab test helps you find causes.
4. Work through What to fix from the top. Each item explains the problem, the fix and how to do it in WordPress.

Field data vs lab data

Field data comes from the Chrome UX Report: 28 days of real Chrome visits, shown at the 75th percentile with the share of good, needs-improvement and poor experiences. If a single URL doesn’t have enough traffic, the tool shows data for your whole site (origin) and says so; new or small sites may have none yet. Lab data is one Lighthouse run on a simulated mid-range phone with a throttled connection. It is repeatable and diagnostic, but it can differ from what users see, and it measures Total Blocking Time instead of INP because no one interacts with the page.

What each metric means and how to fix it

• LCP (Largest Contentful Paint): when the main image or text block appears. Usual fixes: faster server response and caching, a properly sized WebP or AVIF hero image that isn’t lazy-loaded and has fetchpriority="high", and fewer render-blocking CSS and JavaScript files.
• INP (Interaction to Next Paint): how quickly the page responds to taps and clicks. Usual fixes: less JavaScript, fewer third-party widgets and breaking up long tasks.
• CLS (Cumulative Layout Shift): how much content jumps while loading. Usual fixes: width and height on images and embeds, reserved space for ads and banners, and font loading that doesn’t reflow text.
• TTFB and FCP: supporting metrics for server speed and first paint. A slow TTFB on a cached page usually means the hosting needs an upgrade or a CDN.

Frequently asked questions

Speed is one part of the picture: run the free SEO audit and the AI search readiness checker too. If you’d like the fixes done for you, see my services or book a free call.