Core Web Vitals Explained for Business Owners

A slow website costs you visitors before they've read a single word. Google measures part of that experience with Core Web Vitals — three metrics that describe how quickly a page loads, how fast it responds and how stable it looks while loading.

This guide explains Core Web Vitals in plain English, the scores to aim for, and the fixes that make the biggest difference.

What are Core Web Vitals?

Core Web Vitals are three measurements based on how real visitors experience your pages. Google uses them as part of its page experience signals, and they're a useful health check for any website. The official reference is Google's Web Vitals guide.

Metric	What it measures	Good score
LCP — Largest Contentful Paint	How long the main content takes to appear	2.5 seconds or less
INP — Interaction to Next Paint	How quickly the page responds when someone taps or clicks	200 milliseconds or less
CLS — Cumulative Layout Shift	How much the layout jumps around while loading	0.1 or less

To pass, a page should hit the "good" threshold for at least 75% of visits. INP replaced the older First Input Delay (FID) metric in March 2024.

LCP: how fast does the main content load?

LCP is usually your hero image, headline or main banner. If it takes too long, visitors stare at an empty or half-built page.

Common causes of a slow LCP:

• very large, uncompressed images;
• slow server response times;
• render-blocking fonts, CSS or JavaScript;
• the main image loaded late or lazily.

Fixes: compress images and serve modern formats (WebP or AVIF), size them correctly for each screen, load the hero image with high priority, and use fast hosting with caching.

INP: does the page respond quickly?

INP measures the delay between a visitor's action — clicking a menu, opening a form, adding to basket — and the page visibly reacting.

Common causes of a poor INP:

• heavy JavaScript running on the main thread;
• too many third-party scripts (chat widgets, trackers, ad tags);
• complex pages that re-render more than they need to.

Fixes: remove scripts you don't need, load third-party tools after the page is interactive, and split large bundles so only the code a page needs is downloaded.

CLS: does the layout stay still?

Have you ever gone to tap a button just as an advert pushed it down the screen? That's layout shift, and it's frustrating.

Common causes:

• images and videos without set dimensions;
• banners, cookie notices or adverts injected above existing content;
• web fonts that change the size of text once they load.

Fixes: always reserve space for images and embeds, show banners in fixed positions, and use font loading strategies that avoid big jumps.

How to test your Core Web Vitals

1. PageSpeed Insights — enter any URL to see real-user data (when available) and lab test results with specific recommendations.
2. Google Search Console — the Core Web Vitals report groups your URLs into Good, Needs improvement and Poor based on real visits.
3. Chrome DevTools — the Lighthouse and Performance panels help developers find the exact cause of a problem.

Real-user ("field") data is what Google uses. Lab tests are best for diagnosing issues and checking fixes before release.

Do Core Web Vitals affect rankings?

They're one of many signals. Relevant, helpful content still matters most, and a fast page won't outrank a much better answer. But when competing pages are similar, a better experience can help — and faster pages almost always convert more visitors into enquiries and sales.

Quick wins for most business websites

• Compress and resize every image; switch to WebP or AVIF.
• Remove unused plugins, apps and tracking scripts.
• Set width and height on all images and embeds.
• Use good hosting with a CDN and caching.
• Keep fonts to a minimum and preload the ones you use.

Speed is also a core part of technical SEO, so it's worth checking both together.

Want a faster website?

We design and build fast, accessible websites that score well on Core Web Vitals from day one, and we can audit and speed up existing sites. Find out more about our SEO optimisation and UI/UX design services, or ask us for a free performance check.