How To Audit Core Web Vitals

Ella Pybus | 19 May, 2025 | 4 minute read | Blog, SEO

Have you ever wondered why or how to audit Core Web Vitals? Well, slow websites lose potential sales. It’s that simple. Long loading times and poor interaction often lead to bounce rates and fewer conversions. In addition to your Google ranking being affected. 

That’s where Core Web Vitals come in. So, what are core web vitals? They tell you how fast your site loads, how responsive it is and how stable the page is when it loads. If you want to rank well on search engines and keep users engaged on your site (why wouldn’t you?) these metrics matter. 

In this blog, we’ll discuss how to audit Core Web Vitals, why they’re essential for SEO, and how to spot the issues that may be negatively impacting your website. 

What are core web vitals? 

Core web vitals involve 3 elements measured in tools like PageSpeed Insights and the Chrome User Experience Report. Google assesses these to determine your website’s success in this area. 

These 3 elements are: 

• Largest Contentful Paint (LCP)
• Interaction to Next Paint (INP)
• Cumulative Layout Shift (CLS)

These metrics reflect how real user data indicates visitors experience your site, measuring factors like page speed, layout shift (CLS), and how soon users can engage through user input.

Why Your Core Web Vitals Might Be Struggling 

Many sites struggle with their Core Web Vitals tests due to sizes of images, render-blocking scripts, poor hosting, or third-party code (like chat widgets or embedded content). The good news is that most issues are fixable once you know where the problems lie.

Issues like poor CLS scores or high total blocking time  often signal that pages take too long to respond to user interaction, creating a poor user experience.

Are you feeling overwhelmed by auditing core web vitals? Why not go back to the basics? Check out our first blog of the series: how to improve core web vitals

How To Audit Core Web Vitals: Step-by-Step

Auditing your sites core web vitals sounds difficult, but with the right tools it is pretty straightforward. Follow the steps below to get started:

Step 1: Use Google PageSpeed Insights 

Head to PageSpeed Insights and enter your URL. This free tool gives you a Core Web Vitals report, broken down by desktop and mobile. You’ll get real-world data if your site has enough traffic, or lab data (a simulated test) if it doesn’t.

Look for these signals:

• LCP for loading delays (e.g., large banners or images) – Largest Contentful Paint (LCP) measures the render time of the largest visible element.
• INP for slow interactivity (e.g., heavy JavaScript) – this metric recently replaced  First Input Delay (FID). This shows how fast your site responds to user input.
• CLS for elements shifting around as the page loads – Cumulative Layout Shift (CLS) measures how much the web page layout moves unexpectedly, a key component of Core Web Vitals metrics.

The tool highlights which elements are causing issues and how to fix them.

Step 2: Check Google Search Console

Check Google Search Console. Once your site is verified, navigate to the “Core Web Vitals” report under the “Experience” section.

You’ll see URLs marked as “Good,” “Needs Improvement,” or “Poor.” Expand each section to see which pages are affected and by which specific metric.

This is your clearest signal of what real users are experiencing, and it helps prioritise which pages need your attention first.

But remember Google’s Core Web Vitals tools take 28 days to collect real-world data, so don’t expect immediate data.

Step 3: Run a Lighthouse Audit in Chrome 

Open your site in Chrome, right-click, and hit “Inspect.” Under the “Lighthouse” tab, analyse page load. This gives you a more technical breakdown, including performance, accessibility, and SEO recommendations.

Lighthouse can also help you identify high Total Blocking Time (TBT), which often indicates that your website uses a lot of JavaScript, which delays users’ ability to interact with certain parts of your website. 

Lighthouse explains why certain metrics score poorly and offers prioritised suggestions.

Each tool has strengths, and combining them helps you get a fuller picture of your core web vitals. 

Our final thoughts 

Core Web Vitals aren’t just a technical checkbox—they are a clear signal for search engines like Google that your website is fit for purpose and is ready to be served to their users. By auditing them regularly, you ensure your website not only ranks better but also converts more visitors.

If you’re new to the concept, start small. Audit one key page, make a few changes, and monitor the results.

Explore more insights in our blog on how to pass core web vitals and create faster, more user-friendly websites. 

Photo © by prathan chorruangsak.