Core Web Vitals in plain English

What the three actually measure

Largest Contentful Paint is how long before the main thing appears. A visitor's read on whether the site is working.

Interaction to Next Paint is how quickly the page responds when you tap. Slow here feels broken even when it is loading.

Cumulative Layout Shift is how much content jumps while loading. The reason you tap the wrong button.

How much they move rankings

Less than the amount of writing about them suggests. They are a tiebreaker rather than a driver, and a fast page with weak content still loses to a slow page that answers the question.

Where they matter is conversion. A quote form that takes eight seconds to become usable on a phone on mobile data loses people who were ready to call.

What usually causes the failure

Uncompressed hero images. Third-party scripts, especially chat widgets and tag managers carrying tags nobody has audited in two years. Fonts loading late. Ads or embeds reserving no space.

In most trade sites we look at, removing two scripts and compressing the hero image does most of the available work.

The limit

Field data lags. You change something today and the reported score moves over the following weeks, because it is measured from real visits rather than a lab run.

That delay is why chasing the number weekly wastes attention. Fix the causes, then look again next month.

“A quote form that takes eight seconds to become usable on a phone loses people who were ready to call.”