Core Web Vitals

Core Web Vitals are the metrics Google uses to express how a page feels to a real visitor. They're not about how good your site looks, but about three very practical questions: does the main content appear quickly, does the page respond smoothly when you click or type, and does the layout stay stable while it loads? Google uses these figures as part of its assessment of page experience.

Important to know: for these signals, Google relies primarily on data from real users in Chrome, not just on a lab test. So a quick measurement on your own computer with a fibre connection doesn't tell you everything about the experience of a customer on an older smartphone.

Which three metrics are included?

• Largest Contentful Paint (LCP): how long it takes for the largest visible element, often an image or heading, to load. Google uses 2.5 seconds or less as "good".
• Interaction to Next Paint (INP): how quickly the page responds visually to interactions such as clicks or taps. A value under 200 milliseconds is considered good. In 2024, INP replaced the older First Input Delay metric.
• Cumulative Layout Shift (CLS): how much elements shift unexpectedly while the page loads. A score of 0.1 or lower is good.

How much do Core Web Vitals count?

Google says Core Web Vitals count, but that relevant and useful content still carries more weight. A super-fast page with weak content won't suddenly jump to the top. They can, however, make the difference between pages whose content is roughly equivalent. And regardless of rankings, a slow or jumpy page clearly affects your visitors: people drop off sooner and are less likely to complete a conversion.

A fast-loading, technically healthy page is also an advantage for AI crawlers. The systems behind ChatGPT or Perplexity need to be able to fetch and read your content; a site that relies heavily on slow scripts makes that harder.

How to improve your scores

1. Compress images and use modern formats such as WebP or AVIF.
2. Give images and embeds fixed dimensions, so the layout doesn't jump.
3. Cut down on heavy scripts from chat widgets, trackers and sliders you don't really need.
4. Load fonts efficiently and limit the number of variants.
5. Choose solid hosting and use caching.

You'll find more background on loading times under page speed, a broader concept that Core Web Vitals are part of.

A real-world example

An online store selling cycling accessories in Bristol notices in Google Search Console that many product pages are flagged as "needs improvement" on mobile. The cause: large product photos without fixed dimensions and a pop-up that pushes the page down. After optimising the images and adjusting the pop-up, the pages gradually move to "good" over time, as the field data is updated bit by bit.

Where do you start?

Start with the Core Web Vitals report in Search Console and focus on the groups of pages with the most visitors. Core Web Vitals fit into the broader story of technical SEO. With Spacebird's technical SEO analysis, you map out bottlenecks like these, along with other technical issues on your site.