Core Web Vitals Demystified
Google introduced Core Web Vitals as a set of specific metrics that measure real-world user experience on your website. They directly affect your search rankings.
The Three Metrics
1. Largest Contentful Paint (LCP)
What it measures: How quickly the main content of a page loads.
Target: Under 2.5 seconds
In plain English: How long does a visitor wait before they see something useful?
2. Interaction to Next Paint (INP)
What it measures: How quickly the page responds when you click or tap something.
Target: Under 200 milliseconds
In plain English: Does the page feel responsive or laggy?
3. Cumulative Layout Shift (CLS)
What it measures: How much the page layout moves around during loading.
Target: Under 0.1
In plain English: Do things jump around on screen while the page loads?
Why They Matter
Core Web Vitals affect:
- Search rankings — Google uses them as a ranking signal
- User experience — faster, more stable pages keep visitors engaged
- Conversion rates — every second of delay costs you conversions
- Bounce rates — slow pages have significantly higher bounce rates
How to Check Your Scores
You can check your Core Web Vitals for free:
- Google PageSpeed Insights — pagespeed.web.dev
- Google Search Console — look under "Core Web Vitals" report
- Chrome DevTools — Lighthouse tab for detailed analysis
Common Issues and Fixes
Poor LCP:
- Optimise and compress images
- Use a CDN for faster delivery
- Reduce server response time
- Preload critical resources
Poor INP:
- Minimise JavaScript execution
- Break up long tasks
- Reduce third-party scripts
Poor CLS:
- Set explicit dimensions on images and videos
- Avoid inserting content above existing content
- Use font display swap for web fonts
Need Improvement?
If your Core Web Vitals are failing, your website is underperforming in both search and user experience. Performance optimisation is built into every website we create, and we can improve existing sites too. Talk to us about a performance audit.