Core Web Vitals Checker
Bulk-check LCP, TBT and CLS across up to 20 URLs — mobile or desktop.
What Core Web Vitals measure
Core Web Vitals are the three metrics Google uses to judge how a real visitor experiences your page: how fast the main content loads (LCP), how responsive the page feels while it's busy (TBT, standing in for interactivity), and whether the layout stays stable as things load in (CLS).
LCP · Loading
≤ 2.5s is good
How long it takes the largest visible element to render.
TBT · Interactivity
≤ 150ms is good
How long the main thread is blocked from responding to input.
CLS · Stability
≤ 0.1 is good
How much visible content shifts around as the page loads.
FAQs
Why do mobile and desktop scores differ?
Google tests mobile with a simulated slower CPU and connection to reflect real-world mobile conditions, so mobile scores usually run lower than desktop.
Is this the same as Search Console's Core Web Vitals report?
Not exactly — Search Console shows real-user field data over time; this runs a live lab test on demand, useful for debugging a specific page right now.
How do I fix a poor LCP or CLS score?
For LCP, compress your largest image and cut render-blocking resources. For CLS, reserve space for images and ads before they load.