Core Web Vitals: LCP, CLS, and INP Thresholds Explained

Core Web Vitals

Core Web Vitals are Google's three field metrics for user experience: Largest Contentful Paint for loading, Interaction to Next Paint for responsiveness, and Cumulative Layout Shift for visual stability. They are measured from real visitors over 28 days rather than in a lab, which is why a perfect Lighthouse score can still fail them.

Last reviewed 17 September 2026

The three metrics

LCP, Largest Contentful Paint: when the main content finishes rendering. Good is under 2.5 seconds
INP, Interaction to Next Paint: how quickly the page responds to input. Good is under 200 milliseconds. It replaced FID in 2024
CLS, Cumulative Layout Shift: how much the page jumps while loading. Good is under 0.1

Core Web Vitals thresholds
Metric	Good	Needs improvement	Poor
Largest Contentful Paint	2.5s or less	2.5s to 4.0s	over 4.0s
Cumulative Layout Shift	0.1 or less	0.1 to 0.25	over 0.25
Interaction to Next Paint	200ms or less	200ms to 500ms	over 500ms

Lab scores versus field data

Lighthouse runs one simulated load on a throttled connection. Core Web Vitals are the 75th percentile of your actual visitors over 28 days, on their real devices and networks. A site can score 98 in Lighthouse and still fail in the field because most of its traffic is on mid-range Android phones.

Use the Chrome UX Report for the truth and Lighthouse for diagnosing the cause.

What usually breaks them on a marketing site

Unsized images and embeds cause almost all CLS. Hero images that are not preloaded cause most LCP failures. Third-party tags such as chat widgets, tag managers, and heavy analytics cause most INP failures, and they are the ones nobody wants to remove.

Why it matters for B2B marketing teams

For B2B the honest framing is that speed is a conversion issue with an SEO side effect. Ranking impact is real but modest. Abandonment before a form ever renders is not, and it is invisible in your analytics because those visitors never registered as anything.

Frequently asked questions

Do Core Web Vitals affect rankings?+

They are a ranking signal, but a weak one next to relevance and content quality. The stronger argument for fixing them is conversion: slow, unstable pages lose people before they ever see the offer.

How do you improve Core Web Vitals?+

Fix in this order: give every image explicit width and height to stop layout shift, load the largest above-fold image eagerly with fetchpriority high, then defer or remove third-party scripts. Those three changes resolve most failures on a marketing site.

What replaced FID in Core Web Vitals?+

Interaction to Next Paint replaced First Input Delay in March 2024. FID only measured the delay before processing started; INP measures the full time until the next paint, so it reflects what a user actually experiences. Good is 200 milliseconds or less.