How to Fix Core Web Vitals: LCP, INP and CLS Explained

Core Web Vitals are Google's way of measuring whether your pages feel fast and stable to real users, and they're a ranking factor. If Search Console flags them red, you're losing both experience and visibility. This guide explains what each one measures and, more importantly, exactly how to fix it.

What are Core Web Vitals?

There are three Core Web Vitals, each measuring a different part of the experience:

Do Core Web Vitals affect SEO? Yes. They're part of Google's page experience signals, so passing them supports rankings, and failing them can hold a page back, especially when competitors pass.

How to fix LCP (loading speed)

LCP is usually your hero image or headline. To get it under 2.5 seconds:

• •Optimize the largest image: serve modern formats (AVIF/WebP), size it correctly, and compress it.
• •Preload the LCP image so the browser fetches it early.
• •Remove render-blocking resources: defer non-critical JavaScript and inline critical CSS.
• •Use a CDN and caching so the HTML and assets arrive fast.
• •Self-host fonts and use font-display: swap so text doesn't wait on font downloads.

<!-- preload the hero image so LCP starts immediately -->
<link rel="preload" as="image" href="/hero.avif" fetchpriority="high" />

How to fix INP (responsiveness)

INP measures the delay between a user interaction (tap, click, keypress) and the screen updating. Long JavaScript tasks block the main thread and make the page feel sluggish. To improve INP:

1. 1.Break up long tasks: split heavy work into smaller chunks so the browser can respond between them.
2. 2.Ship less JavaScript: code-split and lazy-load what isn't needed immediately.
3. 3.Defer non-urgent work until after the interaction is handled.
4. 4.Avoid large, expensive re-renders on every keystroke, debounce where it makes sense.

How to fix CLS (visual stability)

CLS happens when content moves after it appears, an image loads and shoves text down, or an ad pops in. Fixing it is mostly about reserving space in advance:

• •Always set width and height (or aspect-ratio) on images and video so the browser reserves space.
• •Reserve space for ads, embeds and banners with a min-height.
• •Avoid inserting content above existing content after load.
• •Preload fonts and use font-display: optional/swap carefully to avoid text reflow.

The most common CLS bug is an image with no dimensions. Add width and height, and the layout stops jumping. It's often a one-line fix.

How to measure Core Web Vitals

Measure with real tools, not just your fast laptop:

• •PageSpeed Insights: field data (real users) plus lab diagnostics for a single URL.
• •Google Search Console: the Core Web Vitals report shows which page groups pass or fail across your whole site.
• •Chrome DevTools Lighthouse and the Performance panel: for debugging specific issues locally.

The short version

Fix LCP by optimizing and preloading the largest image and removing render-blockers. Fix INP by shipping less JavaScript and breaking up long tasks. Fix CLS by giving images and dynamic content reserved space. Measure with PageSpeed Insights and Search Console field data, and re-check after each change.

Most Core Web Vitals failures come down to a handful of fixable causes: an unoptimized hero image, too much JavaScript, and images without dimensions. Fix those three and the green usually follows without a full rebuild.