For years, most website owners worried about SEO in terms of keywords and competitive search terms. Those still matter enormously, but Google has added another layer to the mix: Core Web Vitals. These are real-user experience metrics, and they directly influence how your pages rank — which in turn shapes the flow of organic traffic, leads and sales to your business. The good news is that they're very fixable once you know what they measure. Let's walk through them.
- Core Web Vitals measure the real experience visitors have on your pages.
- The three current vitals are LCP (loading), CLS (stability) and INP (responsiveness).
- Aim for LCP ≤ 2.5s, CLS ≤ 0.1 and INP ≤ 200ms across most visits.
- INP replaced First Input Delay as an official vital in March 2024.
What Core Web Vitals are
Core Web Vitals are a set of metrics Google uses to judge the experience real people have when they land on your pages. They're interconnected with the rest of your SEO: improve your vitals and you tend to lift your keyword rankings too. There's a lovely double benefit here — because improving your vitals means improving the underlying user experience, you usually see better engagement and conversion rates as a happy side effect. There are three vitals every site owner should keep an eye on: Largest Contentful Paint, Cumulative Layout Shift and Interaction to Next Paint.
Largest Contentful Paint (LCP)
LCP measures how quickly the main content of a page loads — specifically, the time it takes for the largest image or text block to appear within the viewport. It matters because that big element is almost always the thing the visitor came to see; if it's slow, people leave. Aim for an LCP of 2.5 seconds or less for most visits. To improve it: reduce server response time with caching or faster hosting, use a content delivery network, defer render-blocking JavaScript, and optimise your images. It's closely tied to overall page speed.
Cumulative Layout Shift (CLS)
CLS measures visual stability — how much the content jumps around unexpectedly while a page loads. We've all tried to tap a button only for an ad to load and shove it out of reach; that's exactly what CLS penalises. Aim for a score of 0.1 or less. To improve it: always specify width and height on images and video so the browser reserves the space, load new content (like ads) below the fold rather than above it, and use a CMS with a diagnostic tool such as Lighthouse to flag issues early.
Interaction to Next Paint (INP)
Here's the big update. In March 2024, Google replaced First Input Delay with Interaction to Next Paint (INP) as an official Core Web Vital. Where FID only looked at a visitor's first interaction, INP measures overall responsiveness across all of them — every tap, click and keypress — giving a far more honest picture of how snappy a page feels. Aim for an INP of 200 milliseconds or less. To improve it: defer non-essential JavaScript, break up long tasks, and remove unused CSS so the browser can respond to input faster.
Other metrics worth watching
Alongside the three core vitals, Google's tools report supporting metrics like Total Blocking Time (TBT) — how long the page is blocked from responding to input — and Speed Index (SI), which reflects how quickly content is visually displayed as the page loads. You'll also see First Contentful Paint. These aren't the headline ranking vitals, but they're excellent diagnostic clues when you're working out why your LCP or INP is struggling.
Optimising your own Core Web Vitals can get fiddly, especially once JavaScript and third-party scripts enter the picture. Get them right, though, and you're rewarded twice over — better rankings and a smoother site that visitors actually enjoy using. If you'd like a hand sorting yours out, that's exactly the sort of technical work we handle.
