What Are Core Web Vitals? Google’s Real Ranking Signals

So, Core Web Vitals. Sounds technical — and, it kind of is — but you should know the basics, because it’s how Google measures what real people experience when they land on your website.

No lab tests. No simulations. Just real users, on real devices, in real-world conditions — the kind with spotty 4G on a moving train.

Google tracks three main things:

1. How fast your content shows up
2. How quickly people can interact with your site
3. Whether your layout jumps around unprovoked while things are still loading

These are more than just technical scores - they directly correlate with user satisfaction and business outcomes like your conversion rates and engagement.

Largest Contentful Paint (LCP)

Largest Contentful Paint (LCP) is all about how fast your main content appears. From the hero image, to your headline, and that big juicy bit people are actually waiting to see.

If you want your LCP to score well, you should aim for under 2.5 seconds. Anything over 4 seconds and people are gone before your page even finishes loading.

The usual culprits slowing you down are massive images, sluggish servers, or scripts that block things from loading.

First Input Delay (FID)

The First Input Delay, also known as FID measures the time between a user clicking something and your site doing something.

If someone taps a button and nothing happens for a second or two, then  a user will assume your site’s broken. A good FID is under 100 milliseconds. If you have a Bad FID, then it’s usually caused by heavy JavaScript. This is where your page looks ready, but it’s still busy sorting itself out on the backend. 

Cumulative Layout Shift (CLS)

Cumulative Layout Shift, also known as CLS, is something we all find rather annoying - you’re about to click a button... and then out of nowhere the whole layout moves and you click something else by mistake!