Core Web Vitals

The Web Vitals tool measures your page's Core Web Vitals - the metrics Google uses as ranking factors for page experience.

The three Core Web Vitals

LCP (Largest Contentful Paint)

Measures loading performance. Specifically, when the largest content element becomes visible.

Thresholds:

• Good: < 2.5 seconds
• Needs improvement: 2.5-4 seconds
• Poor: > 4 seconds

Common LCP elements:

• Hero images
• Large text blocks
• Video poster images

INP (Interaction to Next Paint)

Measures interactivity. How quickly the page responds to user interactions.

Thresholds:

• Good: < 200ms
• Needs improvement: 200-500ms
• Poor: > 500ms

What affects INP:

• JavaScript execution time
• Event handler processing
• Main thread blocking

CLS (Cumulative Layout Shift)

Measures visual stability. How much the page layout shifts during loading.

Thresholds:

• Good: < 0.1
• Needs improvement: 0.1-0.25
• Poor: > 0.25

Common causes:

• Images without dimensions
• Dynamically injected content
• Web fonts causing reflow

Running a test

1. Enter the URL to test
2. Choose device type (mobile/desktop)
3. Click "Analyze"
4. Review results for each metric

Lab vs Field data

The tool provides lab data (simulated). For real-user data:

• Check Google Search Console
• Use Chrome User Experience Report
• Implement Real User Monitoring (RUM)

Optimization recommendations

For each metric, the tool provides:

• Current score with pass/fail status
• What element is causing issues
• Specific recommendations to fix
• Priority level for each fix

Track improvements

Create a free account to save your Web Vitals results and track improvements over time. Add your site as a project to see score trends across all audits.