What are the three Core Web Vitals?

LCP (Largest Contentful Paint): how fast the main content loads (Good: < 2.5s). CLS (Cumulative Layout Shift): how much the page jumps around while loading (Good: < 0.1). INP (Interaction to Next Paint): how responsive the page is to user interactions (Good: < 200ms).

Do Core Web Vitals directly affect Google rankings?

Yes. Core Web Vitals are part of Google's Page Experience signal, which is a confirmed ranking factor. While content relevance is still the primary ranking factor, two pages of similar quality will be ranked differently based on their Core Web Vitals performance.

What is the difference between lab data and field data for Core Web Vitals?

Lab data is measured in controlled conditions (like FixTools or Lighthouse) and is useful for development and debugging. Field data is collected from real users via the Chrome UX Report (CrUX). Google uses field data for ranking, but lab data helps identify and fix issues.

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Core Web Vitals Checker

Q: Do Core Web Vitals directly affect Google rankings?

Yes. Core Web Vitals are part of Google's Page Experience signal, which is a confirmed ranking factor. While content relevance is still the primary ranking factor, two pages of similar quality will be ranked differently based on their Core Web Vitals performance.

Q: What is the difference between lab data and field data for Core Web Vitals?

Lab data is measured in controlled conditions (like FixTools or Lighthouse) and is useful for development and debugging. Field data is collected from real users via the Chrome UX Report (CrUX). Google uses field data for ranking, but lab data helps identify and fix issues.

Core Web Vitals are Google's official page experience metrics — LCP (loading), CLS (visual stability), and FID/INP (interactivity). Failing these thresholds directly impacts your search rankings. FixTools checks all three for any URL instantly.

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LCP, CLS, and FID/INP measurement

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Pass/fail threshold indicators

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How to use this tool

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Enter your URL to check all three Core Web Vitals against Google's Pass/Needs Improvement/Fail thresholds.

How It Works

Step-by-step guide to core web vitals checker:

1
Enter your URL
Paste the page URL you want to check. Test your highest-traffic and most commercially important pages.
2
Review the three Core Web Vitals
Check LCP (Good: < 2.5s), CLS (Good: < 0.1), and INP (Good: < 200ms). Note which metrics are in the Poor range.
3
Identify the root cause of failing metrics
Use the detailed report to identify which resources or elements are causing each failing metric.
4
Implement fixes and re-test
Make targeted improvements to failing metrics. Re-test after each fix to measure progress.

Real-world examples

Common situations where this approach makes a real difference:

SEO ranking investigation

A site owner noticing a rankings drop after a Google algorithm update checks Core Web Vitals and discovers CLS has increased from 0.05 to 0.35 after a third-party ad script was added. Removing the ad script restores the previous ranking position within weeks.

New theme deployment

A WordPress site owner testing a new theme before activation checks Core Web Vitals on the staging version. The new theme's hero image causes LCP of 5.2 seconds. They fix the image before switching the theme live.

Quarterly CWV reporting

An agency delivers a quarterly Core Web Vitals report to each client showing before/after changes across all three metrics. FixTools enables them to check all client sites rapidly without running Lighthouse manually on each.

When to use this guide

Use this to diagnose Page Experience issues that may be holding back your search rankings, or to verify that recent optimisations have moved your Core Web Vitals into the "Good" range.

Pro tips

Get better results with these expert suggestions:

LCP is the most impactful metric to fix

LCP (Largest Contentful Paint) measures when the main content of a page is visible. It has the highest weighting in the Lighthouse score and the most direct correlation with user perception of page speed. Fix LCP first.

CLS is often caused by images or ads without dimensions

Cumulative Layout Shift (CLS) measures unexpected page movement while loading. The most common cause is images, ad slots, or embedded content loading without specified width and height attributes, causing content below to jump.

INP replaced FID in March 2024

Interaction to Next Paint (INP) replaced First Input Delay as the interactivity Core Web Vital in March 2024. INP measures the full interactivity of the page across all interactions, not just the first one.