Core Web Vitals, explained without the jargon
Core Web Vitals are three measures Google uses to describe how a page feels to real people. You don't need to write code to understand them, and they're worth understanding, because they describe things your customers notice even if they don't have names for them.
The three measures
| Measure | What it asks | Good is | | --- | --- | --- | | LCP, Largest Contentful Paint | How quickly does the main content appear? | 2.5 seconds or less | | INP, Interaction to Next Paint | When I tap something, how quickly does the page respond? | 200 milliseconds or less | | CLS, Cumulative Layout Shift | Does the page jump around while I'm reading? | 0.1 or less |
Those thresholds are assessed at the 75th percentile of real visits. In plain terms, at least three in four visits should reach "good" for the page to pass.
What usually goes wrong
LCP is most often a huge image, slow hosting, or a web font holding up the headline. Modern image formats, correctly sized files and decent hosting fix most of it.
INP usually means too much JavaScript. Every chat widget, tracker and animation library has a cost, and it's paid on your customers' phones, which are slower than your laptop.
CLS is what happens when you go to tap a button and an image loads above it, pushing it down so you hit an ad instead. The fix is reserving space for images and embeds before they load.
How to check your site
- Go to PageSpeed Insights and enter your address.
- Look at the top section first: the data from real visitors. If there isn't enough traffic for this, you'll only see the lab test below it.
- Check mobile, not just desktop. It's normally the slower and more important of the two.
The lab score out of 100 gets all the attention, but it's a simulated test on one simulated phone. The field data shows what your visitors actually experience, and that's what counts for Google's page experience signals.
How much it matters
Let's be honest about this. Core Web Vitals are a part of how Google assesses page experience, but relevant, useful content still matters more for ranking. A fast page with nothing to say won't outrank a slower page that answers the question.
The stronger reason to care is your visitors. A page that loads quickly, responds straight away and stays still when you try to use it is simply more pleasant and more trustworthy. That's worth having regardless of what any algorithm thinks.