What are Core Web Vitals?

Core Web Vitals are three specific metrics Google uses to measure how users experience your web pages: Largest Contentful Paint (LCP), First Input Delay (FID), and Cumulative Layout Shift (CLS). Together they measure loading speed, interactivity, and visual stability.

Google officially uses these metrics as ranking factors. Pages that provide a good user experience on these measures can rank higher than pages with poor Core Web Vitals scores.

The Three Metrics

Largest Contentful Paint (LCP) measures how long it takes for your main content to load. You want this under 2.5 seconds. This is essentially your page speed for the biggest element on the page.

First Input Delay (FID) measures how quickly your page responds when someone tries to interact with it. It should be under 100 milliseconds. This prevents the frustrating experience of clicking something but nothing happening.

Cumulative Layout Shift (CLS) measures how much your page content moves around while loading. You want a score under 0.1. This prevents buttons moving right as you try to click them or text jumping as images load.

Why They Matter

Poor Core Web Vitals create a frustrating user experience. When your page is slow to load, unresponsive, or jumpy, visitors leave. This increases your bounce rate and decreases dwell time, sending negative signals to Google.

Google wants to rank pages that users actually enjoy using. Core Web Vitals are an attempt to objectively measure that experience.

How to Improve Them

For LCP, optimize your images and use a fast web host. The biggest content element is usually your header image or hero section.

For FID, reduce JavaScript that blocks interactivity. Remove plugins or scripts you don't need.

For CLS, specify width and height attributes for all images and videos. Reserve space for ads or embeds so content doesn't jump when they load.

Check your scores in Google Search Console under the Core Web Vitals report. Focus on fixing issues that affect the most pages first.