What Is Core Web Vitals and How Do They Affect Your Google Ranking?

In 2021, Google officially made Core Web Vitals a ranking factor. This means the user experience metrics on your website now directly affect where you appear in Google search results.

Here's everything you need to know.

What Are Core Web Vitals?

Core Web Vitals are a set of specific metrics Google uses to measure the real-world user experience of a web page. They focus on three aspects: loading, interactivity, and visual stability.

The Three Core Web Vitals

1. Largest Contentful Paint (LCP)

What it measures: Loading performance — how quickly the largest visible content element loads.

Target: Under 2.5 seconds Poor: Over 4 seconds

The 'largest content' is usually a hero image, video, or large text block.

What affects LCP:

• Slow server response times
• Large images that aren't optimised
• Render-blocking JavaScript and CSS
• Slow font loading

2. Interaction to Next Paint (INP)

What it measures: Responsiveness — how quickly the page responds to user interactions (clicks, taps, key presses).

Target: Under 200ms Poor: Over 500ms

INP replaced First Input Delay (FID) as a Core Web Vital in March 2024.

What affects INP:

• Heavy JavaScript execution
• Long tasks blocking the main thread
• Inefficient JavaScript

3. Cumulative Layout Shift (CLS)

What it measures: Visual stability — how much unexpected layout movement occurs during page loading.

Target: Under 0.1 Poor: Over 0.25

You've experienced poor CLS when you go to click a button and the page shifts, causing you to click something else.

What causes layout shifts:

• Images without specified dimensions
• Ads or embeds loading late and pushing content
• Web fonts loading late and changing text size
• Dynamic content insertion

How to Check Your Core Web Vitals

1. Google Search Console — Performance > Core Web Vitals report (field data from real users)
2. PageSpeed Insights — pagespeed.web.dev (lab data + field data)
3. Chrome DevTools — Lighthouse audit

How Core Web Vitals Affect Rankings

Google uses Core Web Vitals as a tiebreaker — when all other things are equal, the page with better Core Web Vitals will rank higher.

In practice, this means:

• Pages with 'Poor' ratings are at a significant disadvantage
• Pages with 'Good' ratings have an advantage over 'Needs Improvement'

Improving Your Core Web Vitals

For LCP:

• Compress and properly size images
• Use a CDN
• Upgrade your hosting
• Reduce server response time

For INP:

• Minimise and defer JavaScript
• Remove unnecessary scripts and plugins

For CLS:

• Always set width and height on images
• Reserve space for ads and dynamic content
• Avoid inserting content above existing content

We Optimise Core Web Vitals on Every Website

At OWD Web Design, Core Web Vitals optimisation is built into every project. Get in touch for a free assessment.