Core Web Vitals Explained (Without the Jargon)
"Core Web Vitals" sounds like something only a developer needs to understand, but it's really just Google measuring what any visitor already feels: does the page load fast, does it respond when I tap something, and does it stay still while I'm reading it? Here's what the three actual metrics mean.
What Core Web Vitals Actually Are
They're a set of three specific measurements Google uses to judge real-world page experience, and they factor into how well a page ranks. Unlike most SEO advice, these aren't guesswork — they're precise, measurable numbers Google collects from real visits to your site.
LCP: How Fast Does the Page Feel Like It's Loaded?
Largest Contentful Paint measures how long it takes for the main, largest piece of content — usually a hero image or heading — to appear on screen. This is the metric most closely tied to a visitor's gut sense of "is this site fast or slow," and it's the one oversized, uncompressed images damage the most.
INP: How Responsive Is It When Someone Actually Uses It?
Interaction to Next Paint measures the delay between a visitor clicking or tapping something and the page actually responding. A site that looks fully loaded but lags when you try to use it — a menu that's slow to open, a button that takes a beat to react — scores poorly here even if it loaded quickly.
CLS: Does the Page Jump Around While Loading?
Cumulative Layout Shift measures how much content unexpectedly moves around as a page loads — an image popping in and pushing text down just as you were about to tap something below it, for example. It's usually invisible until it makes you misclick, at which point it's very noticeable.
What Usually Causes Poor Scores
In our experience, the same handful of culprits show up again and again: unoptimised images (by far the most common), too many render-blocking scripts loading before the page can display anything, and images or ads without reserved space that shove content around as they load in.
Why This Affects More Than Just Rankings
Even ignoring SEO entirely, poor Core Web Vitals scores correlate directly with visitors leaving before converting — nobody consciously thinks "this LCP is too high," they just get impatient and click away. Fixing these numbers and improving the actual visitor experience are, in practice, the same task. It's part of what we check on every website build — see our pricing guide for what's included.