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Core Web Vitals Checker — Simulate LCP, CLS & FID Metrics Online

Simulate and understand your Core Web Vitals scores — Largest Contentful Paint (LCP), Cumulative Layout Shift (CLS), and First Input Delay (FID) — with optimization tips.

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What You Can Do

✅ LCP, CLS, FID simulation

✅ Green / needs improvement / poor thresholds

✅ Optimization tip per metric

✅ Mobile vs desktop comparison

✅ Google ranking signal insights

Frequently Asked Questions

What are Core Web Vitals?

Core Web Vitals are three real-world performance metrics Google uses as a ranking factor: LCP (load time of largest element), CLS (visual stability), and FID/INP (interactivity).

What is a good LCP score?

LCP under 2.5 seconds is 'Good', 2.5–4.0 seconds 'Needs Improvement', and over 4.0 seconds 'Poor'. Aim for under 2.5s for good SEO.

How do I improve CLS?

Set explicit width/height on images and videos, avoid inserting content above existing content, and use CSS transform animations instead of layout-affecting properties.

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