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Core Web Vitals Explained: LCP, INP and CLS in Plain English

A jargon-free explanation of Google's Core Web Vitals — what LCP, INP and CLS mean, and how to improve each one.

Table of Contents

Core Web Vitals are Google’s way of measuring real-world user experience. There are three, and once you understand them they are not scary at all.

LCP — Largest Contentful Paint

This measures how quickly your main content appears. Aim for under 2.5 seconds.

How to improve LCP

Compress your hero image, serve modern formats like WebP, avoid lazy-loading above-the-fold images, and use fast hosting.

INP — Interaction to Next Paint

This measures how quickly your page responds when someone taps or clicks. Aim for under 200 milliseconds.

How to improve INP

Reduce heavy JavaScript, break up long tasks, and avoid loading scripts you do not need.

CLS — Cumulative Layout Shift

This measures how much the page jumps around as it loads. Aim for under 0.1.

How to improve CLS

Always set width and height on images, reserve space for ads and embeds, and avoid inserting content above existing content.

Why it matters

Good Core Web Vitals mean happier visitors, higher conversions and a small ranking advantage. Poor ones quietly cost you customers.

How to measure your scores

You do not need expensive tools. Two free ones from Google tell you everything most sites need.

PageSpeed Insights

Paste in any URL to see both lab data (a simulated test) and, where available, real-world field data from actual Chrome users. Focus on the field data — that is what Google uses for ranking.

Search Console: Core Web Vitals report

This groups your whole site into pages that are Good, Need Improvement, or Poor, on mobile and desktop, so you can fix issues in batches instead of one page at a time.

Lab data vs field data

Lab data is a controlled test — useful for debugging. Field data is what real visitors experienced over the last 28 days — that is the number that affects rankings. When they disagree, trust the field data and investigate why real users have a slower experience (often slow networks, heavy third-party scripts, or ads).

How often should you check?

For most business sites, a monthly check is plenty — plus a fresh test any time you add a new template, a big feature, or a marketing tag. Speed tends to erode slowly as content and scripts accumulate, so a regular check keeps you honest.

Frequently asked questions

What are good Core Web Vitals scores?

LCP under 2.5s, INP under 200ms, and CLS under 0.1 for most pages.

Do Core Web Vitals affect rankings?

Yes — they are a ranking signal and, more importantly, they affect conversions.

How do I check my scores for free?

Use Google PageSpeed Insights and the Core Web Vitals report in Search Console.

Conclusion

You do not need to be an engineer to care about this — you just need a site built the right way. Our website development builds pass Core Web Vitals by default.

Not sure what to do next?

Get a free review of your website and SEO opportunities. We’ll tell you what to fix first.

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