Free Core Web Vitals Reference Guide

Interactive reference for LCP, INP, CLS, FCP, and TTFB. Enter your metric values to see if they pass Google threshold requirements.

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LCP

Largest Contentful Paint

Measures loading performance. Time for the largest visible element to load.

Good: ≤2.5sNeeds: ≤4sPoor: >4s

INP

Interaction to Next Paint

Measures interactivity. Latency of all interactions during the page lifetime.

Good: ≤0.2msNeeds: ≤0.5msPoor: >0.5ms

CLS

Cumulative Layout Shift

Measures visual stability. Sum of all unexpected layout shift scores.

Good: ≤0.1Needs: ≤0.25Poor: >0.25

FCP

First Contentful Paint

Time until the first text or image is painted.

Good: ≤1.8sNeeds: ≤3sPoor: >3s

TTFB

Time to First Byte

Time from page request to first byte of response received.

Good: ≤0.8sNeeds: ≤1.8sPoor: >1.8s

Core Web Vitals are the metrics Google uses to assess page experience. LCP, INP, and CLS are the three primary CWVs that affect search ranking. Measure your values using Chrome DevTools, Lighthouse, or PageSpeed Insights.

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