Core Web Vitals: How to Pass Google's Page Experience Test
Core Web Vitals are three metrics Google uses to measure page experience: Largest Contentful Paint (LCP), which measures loading speed and should be under 2.5 seconds; Interaction to Next Paint (INP), which measures responsiveness and should be under 200 milliseconds; and Cumulative Layout Shift (CLS), which measures visual stability and should be under 0.1. Passing all three signals a fast, stable, responsive page, which supports both rankings and conversions.
What Core Web Vitals are, why they matter for SEO, and how to improve LCP, INP and CLS so your South African website passes Google's page experience test.
TL;DR: Quick Answer
Basic South African brochure sites: R8,000-R20,000. Custom business websites with SEO and copywriting: R20,000-R50,000. E-commerce: R40,000-R150,000+. The five cost drivers that create the biggest price variation are: scope and number of pages, custom vs template design, professional copywriting, integrations (payment gateways, booking systems, CRM), and on-page SEO included at build stage. Always add 15-25% for hosting, maintenance and content updates in year one.
Key takeaways
- Very cheap quotes (under R5,000) almost always exclude copywriting, SEO, custom design and post-launch support
- Professional copywriting can represent 20-35% of a total website project cost, and is worth it for search visibility
- On-page SEO built into the website at launch costs a fraction of what it costs to retrofit after the site is live
- Hosting, SSL, domain and maintenance add R3,000-R10,000 per year on top of build cost
- E-commerce adds significant cost due to payment gateway integrations, product data, security requirements and checkout UX
- Timeline and client responsiveness directly affect cost: slow feedback rounds extend agency hours
Summary
Core Web Vitals are Google's way of putting numbers to how a page feels to use: does it load quickly, respond promptly, and stay visually stable? They are a real ranking factor and, just as importantly, they affect whether visitors stay or leave. This guide explains each of the three metrics in plain language, what good scores look like, the common causes of poor scores, and the practical fixes that move the needle, written for South African sites where mobile and variable connections make performance especially important.
What Core Web Vitals are
Core Web Vitals are three specific metrics Google uses to quantify page experience. They are part of how Google assesses pages, and they map to things real users feel: how fast the main content appears, how quickly the page responds when you interact with it, and whether things jump around as the page loads. Google provides this data through tools like PageSpeed Insights and Search Console, based on both lab tests and real-world user data.
The three metrics explained
Largest Contentful Paint (LCP) — loading
LCP measures how long it takes for the largest visible element, usually a hero image or main heading, to load. A good LCP is under 2.5 seconds. Slow LCP usually comes from large unoptimised images, slow servers or render-blocking resources.
Interaction to Next Paint (INP) — responsiveness
INP measures how quickly the page responds when a user interacts, such as tapping a button. A good INP is under 200 milliseconds. Poor INP usually comes from heavy JavaScript that blocks the browser from responding promptly.
Cumulative Layout Shift (CLS) — visual stability
CLS measures how much the page layout unexpectedly shifts as it loads, the frustrating experience of going to tap something just as it jumps. A good CLS is under 0.1. It is usually caused by images or ads without reserved space, or fonts that load late.
Why they matter
Core Web Vitals matter for two reasons. First, they are a ranking signal: Google uses page experience as a factor, so poor scores can hold back pages that are otherwise well-optimised. Second, and often more importantly, they affect conversion. South African users, frequently on mobile and variable connections, abandon slow and janky pages quickly. A faster, more stable site keeps more visitors and converts more of them.
The real prize: Even setting SEO aside, improving Core Web Vitals usually lifts conversions, because the same things that please Google please your visitors.
How to improve your scores
- Optimise images: compress them, use modern formats like WebP, and serve appropriately sized images for mobile.
- Reserve space for media: set dimensions for images and ad slots so the layout does not shift (fixes CLS).
- Reduce and defer JavaScript: trim heavy scripts and load non-essential ones later to improve INP.
- Use good hosting and a CDN: faster server response and nearby delivery improve LCP.
- Eliminate render-blocking resources: load critical content first and defer the rest.
- Preload key assets and fonts: so the main content and text appear quickly and stably.
How to measure and monitor
Use Google PageSpeed Insights to test individual pages and see specific recommendations, and use the Core Web Vitals report in Google Search Console to monitor your whole site over time using real user data. Fix the worst-performing templates first, since improving a page template lifts every page that uses it. Treat Core Web Vitals as an ongoing maintenance item, not a once-off project, because new content and changes can erode scores over time.
Related Juicy Designs resources
- Website development services
- What are Core Web Vitals? (glossary)
- Website maintenance services
- Technical SEO audit checklist
Frequently asked questions
What are Core Web Vitals?
Core Web Vitals are three metrics Google uses to measure page experience: Largest Contentful Paint (loading speed), Interaction to Next Paint (responsiveness) and Cumulative Layout Shift (visual stability). Together they quantify how fast and stable a page feels to use.
What are good Core Web Vitals scores?
Aim for Largest Contentful Paint under 2.5 seconds, Interaction to Next Paint under 200 milliseconds, and Cumulative Layout Shift under 0.1. Meeting all three thresholds means your page passes Google's page experience assessment.
Do Core Web Vitals affect SEO?
Yes. Google uses page experience, including Core Web Vitals, as a ranking signal. Poor scores can hold back otherwise well-optimised pages. Just as importantly, better scores usually improve conversions because faster, stabler pages keep more visitors.
How do I improve my Core Web Vitals?
Optimise and properly size images, reserve space for media to prevent layout shifts, reduce and defer heavy JavaScript, use fast hosting and a CDN, eliminate render-blocking resources, and preload key assets and fonts.
How do I check my Core Web Vitals?
Use Google PageSpeed Insights to test individual pages and get specific recommendations, and the Core Web Vitals report in Google Search Console to monitor your whole site over time using real-world user data.
Why is Cumulative Layout Shift important?
Cumulative Layout Shift measures how much a page's layout unexpectedly moves while loading. High CLS creates the frustrating experience of content jumping as you try to tap it. Keeping CLS under 0.1 makes pages feel stable and trustworthy.