Google uses "Core Web Vitals" to measure how fast and stable your website feels to visitors. These metrics affect your search rankings and, more importantly, whether visitors stay on your site. Here's what you need to know — in plain English.
What Are Core Web Vitals?
Core Web Vitals are three specific measurements Google uses to evaluate user experience:
- LCP (Largest Contentful Paint) — Loading speed
- INP (Interaction to Next Paint) — Responsiveness
- CLS (Cumulative Layout Shift) — Visual stability
Think of it like judging a restaurant: How quickly do you get served (LCP)? How responsive is the staff (INP)? Does your table keep wobbling (CLS)?
LCP: Largest Contentful Paint
What It Measures
How long until the main content on your page appears. Usually, this is your hero image or main heading.
The Target
Good: Under 2.5 seconds
Needs Improvement: 2.5-4 seconds
Poor: Over 4 seconds
Why It Matters
People are impatient. If your page takes forever to show content, they leave. Google knows this and factors it into rankings.
Common LCP Problems
- Large, unoptimised images
- Slow server response
- Render-blocking JavaScript
- Slow-loading fonts
How to Improve LCP
- Optimise and compress images
- Use modern image formats (WebP)
- Upgrade to faster hosting
- Preload your largest image
- Minimise render-blocking resources
INP: Interaction to Next Paint
What It Measures
How quickly your site responds when someone clicks, taps, or types. It replaced the older FID (First Input Delay) metric in 2024.
The Target
Good: Under 200 milliseconds
Needs Improvement: 200-500 milliseconds
Poor: Over 500 milliseconds
Why It Matters
When someone clicks a button and nothing happens for a second, it feels broken. Responsive sites feel professional; sluggish sites feel cheap.
Common INP Problems
- Heavy JavaScript execution
- Too many scripts running
- Inefficient event handlers
- Third-party scripts (analytics, chat widgets)
How to Improve INP
- Reduce JavaScript on the page
- Remove unnecessary scripts
- Defer non-critical JavaScript
- Optimise third-party scripts
- Use efficient code practices
CLS: Cumulative Layout Shift
What It Measures
How much the page layout moves around while loading. Have you ever tried to click a button, but the page shifted and you clicked something else? That's layout shift.
The Target
Good: Under 0.1
Needs Improvement: 0.1-0.25
Poor: Over 0.25
Why It Matters
Layout shifts are frustrating. They make your site feel unstable and can cause users to click the wrong thing. It's a terrible user experience.
Common CLS Problems
- Images without dimensions
- Ads or embeds that load late
- Fonts that swap after loading
- Dynamic content inserted above existing content
How to Improve CLS
- Always specify image dimensions
- Reserve space for ads and embeds
- Use font-display: swap carefully
- Don't insert content above existing content
How Core Web Vitals Affect SEO
Google confirmed Core Web Vitals are a ranking factor. While content quality still matters more, page experience is the tiebreaker.
If two pages have equally good content but one loads faster and feels smoother, the faster one ranks higher.
Beyond rankings, good Core Web Vitals mean:
- Lower bounce rates
- Higher engagement
- Better conversion rates
- Improved user satisfaction
How to Check Your Core Web Vitals
Google PageSpeed Insights
Free tool at pagespeed.web.dev. Enter your URL and get scores plus recommendations.
Google Search Console
The "Core Web Vitals" report shows real-world data from actual users across your entire site.
Chrome DevTools
For developers, Chrome's Lighthouse tool provides detailed performance analysis.
What's a Good Score?
For most businesses, aim for:
- PageSpeed Score: 90+ on desktop, 70+ on mobile
- LCP: Under 2.5 seconds
- INP: Under 200 milliseconds
- CLS: Under 0.1
Mobile scores are typically lower than desktop — that's normal. Focus on mobile since that's what Google prioritises.
Quick Wins for Better Scores
1. Optimise Images
The biggest impact for most sites. Compress images, use modern formats, specify dimensions.
2. Reduce Third-Party Scripts
Every chat widget, analytics tool, and social embed slows your site. Keep only what's essential.
3. Upgrade Hosting
Cheap shared hosting often has slow server response times. Better hosting improves LCP significantly.
4. Lazy Load Below-Fold Content
Don't load images and videos that aren't visible until users scroll to them.
5. Minimise Layout Shifts
Reserve space for all images and embeds. Don't insert content above existing content.
Do Core Web Vitals Really Matter?
Yes, but context matters:
They matter most when:
- You're in a competitive search market
- You rely heavily on organic traffic
- Your target audience has slower connections
- You're an eCommerce site (speed = sales)
They matter less when:
- You have limited competition
- Traffic comes mainly from referrals or direct
- Your content is uniquely valuable
- You're in a niche with few alternatives
Even if SEO isn't critical for your business, fast sites convert better. Every second of load time costs you money.
Our Approach
At Blu Mint Digital, every website we build is optimised for Core Web Vitals from the start. We use modern frameworks, optimise images automatically, and follow performance best practices.
Our sites typically score 90+ on PageSpeed Insights because we build performance in from day one, rather than trying to fix it later. That's the advantage of Next.js development over a plugin-heavy build, and it's a core part of our SEO and digital growth work. If your current site is slow, our technical SEO checklist for new websites covers the foundations that move these scores.
Want to know how your site scores — and what's dragging it down? Get in touch.
Frequently Asked Questions
What are Core Web Vitals?
Core Web Vitals are three Google metrics that measure real-world user experience: Largest Contentful Paint (LCP, loading speed), Interaction to Next Paint (INP, responsiveness), and Cumulative Layout Shift (CLS, visual stability). They're a confirmed ranking signal.
What is a good Core Web Vitals score?
Google's "good" thresholds are LCP under 2.5 seconds, INP under 200 milliseconds, and CLS under 0.1. You can check your scores free in PageSpeed Insights or the Core Web Vitals report in Google Search Console.
Do Core Web Vitals really affect SEO?
Yes, but as a tiebreaker rather than the dominant factor — relevant content still comes first. Where they matter most is competitive markets and eCommerce, where speed directly affects both rankings and conversions.
How do I improve my Core Web Vitals?
Optimise and properly size images, reduce unused scripts and heavy plugins, use quality hosting and a CDN, and reserve space for images and ads to prevent layout shift. The most reliable fix is building on a fast framework from the start.