Core Web Vitals Explained for Business Owners

Your developer mentions Core Web Vitals, your agency puts it in a proposal, and Search Console shows a report you have never opened. Here is what the three metrics actually measure and what to do about them.

LCP — Largest Contentful Paint

How long until the biggest thing on screen appears. Usually the hero image or the main headline. This is the closest metric to what a visitor means by “the page loaded”.

Aim for under 2.5 seconds. The usual cause of a bad LCP is an enormous unoptimised hero image, followed by slow server response.

INP — Interaction to Next Paint

How quickly the page responds when someone taps or clicks. If a visitor taps a menu and nothing happens for half a second, they tap again, and now the menu opens and closes.

Aim for under 200 milliseconds. Bad INP is almost always too much JavaScript competing for the main thread — often from plugins or third-party scripts rather than anything you asked for.

CLS — Cumulative Layout Shift

How much the page jumps around while loading. You go to tap a link, an image finishes loading above it, everything moves down, and you tap an ad instead.

Aim for under 0.1. The usual causes are images without declared dimensions, ads and embeds inserted without reserved space, and fonts swapping in at a different size.

How much do they matter for rankings?

They are a real ranking factor and a modest one. Relevance, content quality and links matter considerably more. Passing Core Web Vitals will not lift a thin page above a comprehensive one.

Where they matter is as a tiebreaker between comparable pages, and — far more importantly — for conversion. People leave slow sites. That effect is larger and more immediate than any ranking movement.

So: worth fixing, not worth obsessing over past the thresholds.

Field data, not lab data

Testing tools give you a lab score from a simulated device. Search Console gives you field data from real visitors on real phones and real networks. When they disagree, believe the field data — it is the one Google uses and the one describing your actual customers.

What to ask your developer

• Are we passing all three on mobile, in field data?
• What is our LCP element and how large is it?
• Which scripts are the biggest contributors to INP?
• Do all images have width and height declared?
• What would it take to pass, and what would it cost?

If the answer to the first question is a lab score from a testing tool, ask again more specifically.