Core Web Vitals explained, in plain English.
LCP, INP, and CLS. These are the three numbers Google uses to rank your site on page experience. Here is what each one measures, what the targets are, and how to fix yours. INP replaced FID in March 2024.


Why Google invented Core Web Vitals.
Before Core Web Vitals, Google measured site speed with a single number, page load time which did not reflect how sites actually feel to visitors. CWV replaced that with three specific metrics that measure real user experience: how fast does the main content appear (LCP), how fast does the page respond to a tap (INP), and does the layout shift around while loading (CLS).
- LCP. Largest Contentful Paint, target under 2.5s
- INP. Interaction to Next Paint, target under 200ms (replaced FID)
- CLS. Cumulative Layout Shift, target under 0.1
The three metrics, explained.
Our AI analyzes your Core Web Vitals alongside 50+ other performance metrics to identify exactly what's slowing your site down.

Largest Contentful Paint
How long until the main content shows. Target under 2.5s. Usually fixed by optimizing hero images and fonts.
- Identifies which element is your LCP (often hero images or headings)
- Measures load time on mobile and desktop separately
- Recommends specific fixes like image compression or lazy loading

Interaction to Next Paint
How responsive your page is to taps and clicks. Target under 200ms. Usually a JavaScript problem. Replaced FID in March 2024.
- Detects blocking JavaScript that delays interactivity
- Measures response time for first user interaction
- Suggests script optimization or deferral strategies

Cumulative Layout Shift
How much your layout jumps around while loading. Target under 0.1. Usually caused by unoptimized images, ads, or web fonts.
- Identifies elements causing layout shifts (ads, images, fonts)
- Calculates total shift score across page load
- Recommends size attributes for images and reserved space for dynamic content
How SchemaReports measures Core Web Vitals.
SchemaReports fetches your live page in a browser context and measures LCP, INP, and CLS the same way Chrome does for real users. Not simulated. Not cached. Real values on the live site. Every slow element is identified by selector. Phase 1 of every audit, free or paid.
- Live measurement, not simulation
- Element-level identification
- Specific fix recommendations

Core Web Vitals, common questions
Common questions about Google's performance metrics and how we measure them.
Do Core Web Vitals actually affect rankings?
Yes, they are a confirmed Google ranking signal as part of the page experience update.
- Same measurement tools Google uses for ranking decisions
- Both mobile and desktop scores analyzed separately
What is a good score?
Under 2.5s LCP, under 200ms INP, under 0.1 CLS.
- Good scores give you a ranking advantage in competitive searches
- Poor scores can push you down even if your content is solid
What happened to FID?
Retired in March 2024 and replaced by INP. INP is a better metric because it measures the entire page lifetime.
- Scores can change when you update plugins or add new content
- Regular tracking shows if your improvements actually worked
Why is TBT not a Core Web Vital?
TBT is a lab metric (measured during development). INP is a field metric (measured from real users). Google ranks on field metrics.
- Most impact in competitive industries where content quality is similar
- Better performance also means better user experience and conversions
Can I use Lighthouse instead?
Lighthouse runs a lab version of the check. SchemaReports runs the live version. Both are useful, live is more accurate.
- Field data shows real-world performance across different devices and connections
- Lab data provides consistent testing for tracking improvements over time
Can I pass Core Web Vitals with a WordPress site?
Yes, but it requires attention to plugins, themes, and hosting. WordPress sites often struggle with Core Web Vitals because of plugin bloat and cheap hosting. Use caching plugins, optimize images, and choose a fast theme.
- Audit your plugins and remove ones you don't actually need
- Better hosting makes a bigger difference than any optimization plugin
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