Core Web Vitals Explained Without the Jargon

Google made Core Web Vitals an official ranking factor in 2021. Behind three cryptic acronyms sits a simple question: does your site appear quickly, respond quickly, and stay still under the user''s finger. Here is what each measures and exactly what to do about it.

LCP — how fast the main content appears

Largest Contentful Paint measures the time until the biggest element on screen renders — usually a hero image or a large heading. Target: under 2.5 seconds. The usual culprits: a slow server (high TTFB), oversized images, and render-blocking scripts. Fixes in order: faster hosting with caching, images converted to WebP and resized to display dimensions, and prioritised loading of the hero image.

INP — how fast the site reacts to a click

Interaction to Next Paint replaced the older FID and measures the delay between a click and a visible response. Target: under 200ms. The culprit is almost always JavaScript: too many plugins, heavy themes, chat widgets and tracking pixels choking the browser. Fix: delete unused plugins, move to a lightweight theme, and defer every third-party script.

CLS — how much the page jumps while loading

Cumulative Layout Shift measures how much elements move as the page loads — that infuriating moment when you go to click a button and it leaps away because an ad loaded above it. Target: under 0.1. The fixes are simple: always specify width and height on images and videos, reserve space for ads and banners, and avoid injecting content above existing content after load.

How to measure your own site

Open PageSpeed Insights and enter your address. Look at the top section ("Discover what your real users are experiencing") — those are the numbers Google actually uses for ranking; the bottom section is a lab test. Google Search Console also has a dedicated Core Web Vitals report showing which groups of pages are failing.

What you can and cannot fix yourself

CLS and INP are largely in your hands — a matter of theme, plugins and discipline. But LCP depends critically on the server: if TTFB exceeds 600ms, even a perfectly optimised site will not reach the green zone. So check your hosting first, then spend time on everything else. Our platform, built on NVMe storage and server-level caching, keeps TTFB under 200ms — more on that here.