How to Improve Core Web Vitals for Better Rankings (2025 Update)

A Beginner-Friendly Step-by-Step Technical SEO Guide

Why Core Web Vitals Matter (2025 Edition)

Google wants users to have a fast and smooth browsing experience.
Core Web Vitals (CWV) are important signals Google uses to measure page experience. If your website fails these, you risk:

• Lower rankings on Google
• Higher bounce rates (users leave faster)
• Fewer conversions and sales

So, if you want to rank higher and retain users → Core Web Vitals are non-negotiable in 2025.

What’s New in 2025?

FID replaced by INP

Google retired “First Input Delay” (FID) and introduced a more precise metric called “Interaction to Next Paint” (INP), which tracks the speed at which users see visual feedback after they interact with your website.

Mobile is Priority #1

Since Google is fully mobile-first, your mobile Core Web Vitals score matters more than desktop.

Performance Budgets Are Key

Websites need to limit how big and heavy pages are → This keeps your site fast.

What Are Core Web Vitals (CWV)?

Core Web Vitals consist of three key performance metrics, each measuring a different aspect of user experience.

Let’s break them down in simple words:

Largest Contentful Paint (LCP) → Loading Speed

What it measures:

How long does the biggest content on your screen take to load (like a big image, banner, or headline)?

Good Score: Under 2.5 seconds
Needs Improvement: 2.5–4 seconds
Poor: Above 4 seconds

How to find your LCP:

1. Go to PageSpeed Insights → Enter your URL → See “Largest Contentful Paint”.
2. (OR) → Open Chrome → F12 → Performance Tab → Record → See LCP.

Common LCP elements:

• Hero images
• Article titles (H1/H2)
• Featured images or banners

Interaction to Next Paint (INP) → Interactivity Speed

What it measures:

When users click, tap, or type, how long does the website take to react?

Good Score: Under 200ms
Needs Improvement: 200–500ms
Poor: Above 500ms

How to check INP:

1. PageSpeed Insights → See “Interaction to Next Paint”
2. Chrome → F12 → Performance → Record user interactions

Common problems:

• Too much JavaScript
• Slow third-party scripts
• Heavy animations

Cumulative Layout Shift (CLS) → Visual Stability

What it measures:

Are there unexpected movements or content shifts occurring as your page loads? (Shifting text, buttons, images etc.)

Good Score: Under 0.1
Needs Improvement: 0.1–0.25
Poor: Above 0.25

How to detect CLS:

1. PageSpeed Insights → See “Cumulative Layout Shift”
2. Chrome DevTools → F12 → Performance → Record → Watch for shifts.

Common reasons for CLS:

• Images without width/height set
• Ads or popups pushing content
• Fonts loading late causing text jumps

How to Measure Core Web Vitals (Tools for Beginners)

Beginner Tip:
Start with PageSpeed Insights + Google Search Console → These are the easiest.

How to Improve Core Web Vitals (Step-by-Step Fixes)

Improving Largest Contentful Paint (LCP)

1. Improve how quickly your server delivers the first byte of data (Time to First Byte or TTFB).

Upgrade to a high-performance hosting provider (Kinsta, SiteGround, Cloudways).

1. Enable server-side caching (Varnish, Redis, WP Rocket for WordPress).
2. Use a CDN (Cloudflare, BunnyCDN) to serve static content faster.

How it helps:

When a user requests your website, the first thing they wait for is the server to respond.
If this takes too long → your entire page loading is delayed.
By reducing server response time (using fast hosting, caching, CDN), the first byte reaches faster → entire page starts loading earlier → improves LCP.

2. Optimize Images for Faster Loading

1. Convert images to WebP or AVIF (smaller, faster than PNG/JPG).

How it helps:

These formats are much smaller in file size without losing quality → Smaller images = Less data to download → Page loads faster → LCP improves.

2. Enable lazy loading:

html

<img src="image.webp" loading="lazy" width="600" height="400">

How it helps:

Instead of loading all images at once (even those not visible yet), lazy loading loads images only when users scroll near them.
This reduces the initial load → so the browser focuses on loading only critical elements → improves LCP.

3. Defer Render-Blocking Resources

• Postpone the loading of JavaScript so that the browser can prioritize rendering the HTML content first.

html

<script src="script.js" defer></script>

How it helps:

By deferring JS, browser can first load and render HTML and visible content (LCP element) → then run JS after that.
This prevents JS from blocking the loading → Improves LCP.

Where to add:

→ In your website HTML head or footer (usually via theme or plugin)

• Preload critical CSS

html

<link rel="preload" href="styles.css" as="style">

Where to add:

→ In website header (your theme header.php or plugin)

How it helps:

If CSS is delayed, page cannot be painted (displayed).
Preloading ensures that critical CSS arrives early → faster rendering of important page parts (like hero image/text) → Improves LCP.

Improving Interaction to Next Paint (INP)

Step 1: Minimize JavaScript

• Remove unused JS (check Lighthouse → Unused JS)

How it helps:

Less JS on page → Less code for browser to process → Faster response to user actions (click, tap, scroll) → Improves INP.

• Defer or async non-critical JS:

html

<script src="analytics.js" async></script>

Where to add:

→ In website header or footer (plugin, theme, GTM)

How it helps:

Async/defer tells browser → “You can load this JS later / when free.”
So browser doesn’t pause rendering to load scripts → User can interact faster → Improves INP.

Step 2: Optimize Main Thread Work

• Break heavy scripts using requestIdleCallback

Problem: Long, Blocking Script

JS

// BAD: All tasks in one go, blocks UI
heavyItems.forEach(item => {
  processItem(item); // Long-running
});

Solution: Break into chunks using requestIdleCallback

JS

function processItemsInIdle(items) {
  let index = 0;
  function work(deadline) {
    while (index < items.length && deadline.timeRemaining() > 0) {
      processItem(items[index]);
      index++;
    }
    if (index < items.length) {
      requestIdleCallback(work); // Schedule next chunk
    }
  }
  requestIdleCallback(work);
}
processItemsInIdle(heavyItems);

How it helps:

Long JS tasks block the browser → user clicks, but nothing happens until script finishes.
By breaking tasks → browser gets free moments to respond to clicks → Improves INP.

• Use passive event listeners:

js

document.addEventListener('scroll', event => {
   // optimized code
}, { passive: true });

Where to add:

→ In your JS files or plugin scripts.

How it helps:

Passive listeners tell browser → “This scroll/click listener won’t block scrolling.”
So browser doesn’t wait → User scrolls smoothly → Faster interactions → Improves INP.

Improving Cumulative Layout Shift (CLS)

Step 1: Reserve Space for Images and Ads

• Set explicit width & height in images:

html

<img src="banner.webp" width="1200" height="600">

How it helps:

When dimensions are defined → Browser reserves that space even before image loads → No shifting when image finally appears → Stops layout shift → Improves CLS.

Step 2: Preload Fonts and Use Swap

html

<link rel="preload" href="font.woff2" as="font" type="font/woff2" crossorigin="anonymous">

Where to add:

→ In header (theme or plugin)

How it helps:

Fonts can be large → If delayed, text appears → then jumps when font loads.
By preloading fonts, you instruct the browser to fetch them early, ensuring smooth text display and preventing sudden layout shifts.

AND

css

@font-face {
    font-family: 'MyFont';
    src: url('font.woff2') format('woff2');
    font-display: swap;
}

Where to add:

→ In CSS file or Customizer → Additional CSS

How it helps:

While custom fonts load, browser shows fallback font immediately → No blank space → No layout shift.
Once custom font arrives, it replaces smoothly → Improves CLS.

Final Thoughts (2025 SEO Reality)

Enhancing your Core Web Vitals has become essential — it’s now a must-do to achieve better rankings and offer a smoother user experience.

• Higher Google rankings
• Better user experience
• More conversions and revenue

Focus on Mobile CWV first → Fix LCP → Then INP → Finally CLS

Start with easy fixes like images and lazy loading, then move on to advanced optimizations.

If you need CMS-specific help (WordPress, Shopify, etc.), let me know — I can make this guide CMS tailored too!

And hey — I’d really love to hear your thoughts and feedback in the comments!