Do Core Web Vitals affect rankings?

Yes — they're part of Google's page-experience signals. They are one factor among many; content relevance still dominates.

What replaced First Input Delay (FID)?

INP (Interaction to Next Paint) replaced FID as a Core Web Vital in March 2024. INP measures the full latency of interactions, not just input delay.

Why do lab and field numbers differ?

Lab tests simulate one device and network; field data aggregates thousands of real visits across devices, networks, and locations. Both are useful — field data is what counts.

What is a good Core Web Vitals score?

Core Web Vitals are Google's three user-experience metrics: LCP, CLS, and INP. Here are the thresholds that count as good, and what each metric actually measures.

The three metrics and their thresholds

Largest Contentful Paint (LCP) measures loading: how long until the biggest visible element renders. Good is 2.5 seconds or less; over 4 seconds is poor.

Cumulative Layout Shift (CLS) measures visual stability: how much the page jumps around while loading. Good is 0.1 or less; over 0.25 is poor.

Interaction to Next Paint (INP) measures responsiveness: how quickly the page reacts when a visitor taps or clicks. Good is 200ms or less; over 500ms is poor.

Lab data vs. field data

Lab tests (like Lighthouse) load your page in a controlled environment — repeatable, but simulated. Field data (the Chrome UX Report) comes from real visitors over the previous 28 days. Google's page-experience signals use field data, and a page needs to hit the good threshold for 75% of visits to count as passing.

INP in particular only exists as field data — it needs real interactions from real visitors.

Which one to fix first

Fix whichever metric is worst, but know their causes: LCP problems come from slow servers, large images, and render-blocking resources. CLS comes from images and embeds without reserved space. INP comes from heavy JavaScript. They're mostly independent problems with independent fixes.

Common questions

Do Core Web Vitals affect rankings?: Yes — they're part of Google's page-experience signals. They are one factor among many; content relevance still dominates.
What replaced First Input Delay (FID)?: INP (Interaction to Next Paint) replaced FID as a Core Web Vital in March 2024. INP measures the full latency of interactions, not just input delay.
Why do lab and field numbers differ?: Lab tests simulate one device and network; field data aggregates thousands of real visits across devices, networks, and locations. Both are useful — field data is what counts.

Core Web Vitals, TTFB, page weight — with plain-language fixes.

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