Core Web Vitals, explained for people who run a business, not a server
Google grades every website on three things it never tells your visitors about. Here is what the grades mean, why they move your ranking and your conversion rate, and the one number worth asking any web developer for.
If you have ever seen a "PageSpeed" score, you have met Core Web Vitals. They are the three measurements Google uses to decide whether a page feels fast and stable to a real person. They affect where you rank, and, more importantly, whether the people who do arrive stick around. You do not need to know how to fix them. You do need to know what they are, so you can tell whether you are being sold a fast site or just a pretty one.
The three measurements
Largest Contentful Paint (LCP): how long until the page looks loaded
The time from tapping a link to the biggest thing on screen, usually your headline or hero image, actually appearing. Google wants this under 2.5 seconds. Most business sites we audit sit between four and seven on a phone. Our builds land around one.
Interaction to Next Paint (INP): how quickly the page responds
You tap a menu. How long before something happens? Over 200 milliseconds feels sluggish; over half a second feels broken. Heavy scripts, usually from plugins and trackers, are what push this up.
Cumulative Layout Shift (CLS): does the page jump around
You go to tap a button and the page shifts and you tap an advert instead. That is layout shift. It is caused by images and embeds loading without reserved space. Google wants it near zero. It is also the single most irritating thing a website can do to a visitor.
Why it is money, not just a score
The research on this is unusually consistent. Every extra second of load time on a phone costs roughly a fifth of your visitors before they have read a word. A page that takes five seconds has lost over half the people who clicked. Those were people who wanted what you sell, searched for it, chose you from the results, and left because a spinner was still turning.
Slow is not a technical problem. It is a marketing budget leaking onto the floor.
And because Google uses the same measurements as a ranking signal, a slow site gets fewer visitors to lose in the first place. The effect compounds.
Why most sites are slow
- Builders and themes ship every feature they have, whether your page uses it or not.
- Plugins stack up: a chat widget, a cookie banner, three analytics tools, a font service. Each one is "only" a few hundred kilobytes.
- Images are uploaded straight from a camera at ten times the size the screen needs.
- Cheap shared hosting puts your site on a server with five hundred others.
None of this is visible in the design. A slow site and a fast site can look identical in a screenshot. The difference is entirely in how they are built and where they live.
The one number to ask for
Before you hire anyone to build or rebuild your site, ask for the mobile PageSpeed score of the last site they shipped. Not desktop, mobile. Not a demo, a real client site. Anyone building properly will have it to hand and it will be in the nineties. Anyone who changes the subject has just told you something.
If you would like to know where your current site stands, send us the address. We will run the numbers and tell you plainly, whether or not you ever hire us.