Core Web Vitals are Google's attempt to measure how a page actually feels to a real user — how fast it loads, how quickly it responds, and how stable it is while loading. They're a genuine ranking signal, and just as importantly, they directly affect conversions.
The three metrics that matter
LCP — Largest Contentful Paint (loading)
LCP measures how long until the main content is visible. Aim for under 2.5 seconds. It's usually dominated by your largest image or hero, slow server response, or render-blocking resources.
INP — Interaction to Next Paint (responsiveness)
INP replaced First Input Delay (FID) as a Core Web Vital in March 2024. It measures how quickly the page responds to user interactions — taps, clicks, key presses — across the whole visit. Aim for under 200 milliseconds. Heavy JavaScript is the usual culprit.
CLS — Cumulative Layout Shift (stability)
CLS measures unexpected movement as the page loads — the frustrating jump when a button shifts just as you tap it. Aim for under 0.1. Reserve space for images and ads, and avoid injecting content above existing content.
Passing Core Web Vitals rarely rockets you to #1 on its own — but failing them is a tax on every other ranking and conversion effort you make.
How to actually improve them
- Optimize images: modern formats (WebP/AVIF), correct sizing, and lazy-loading below the fold.
- Cut and defer JavaScript: ship less to the browser, and split code so pages stay interactive — the biggest INP win.
- Use a fast host and a CDN so content is served quickly and close to the user.
- Reserve dimensions for images, embeds, and dynamic content to eliminate layout shift.
- Prioritize the hero: preload the LCP image and avoid render-blocking fonts and scripts.
Why this is also a conversion story
Speed isn't only about Google. Study after study shows that every additional second of load time reduces conversions, and slower sites see higher bounce rates. Improving Core Web Vitals often lifts revenue before it ever moves a ranking.
Measure with real-user data
Lab tools like Lighthouse are useful for debugging, but Google ranks on field data from real users (the Chrome UX Report). Check Search Console's Core Web Vitals report to see how actual visitors experience your site, then fix the templates that fail.
We build in Next.js specifically to win here — sub-second loads and lean JavaScript by default. If your site feels slow, a free teardown will show you exactly which metric is costing you traffic and sales.