Test page speed and Core Web Vitals for any URL. Get LCP, FCP, CLS, TBT scores with actionable optimization recommendations.
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Get StartedPage speed is one of the most impactful technical SEO factors. Google has used site speed as a ranking signal since 2010, and the introduction of Core Web Vitals in 2021 made performance metrics an explicit, measurable component of Google's ranking algorithm. Pages that load slowly lose visitors -- Google's research shows that as page load time increases from 1 to 3 seconds, the probability of bounce increases by 32%, and by 5 seconds, it jumps to 90%.
Beyond rankings, page speed directly impacts conversion rates. Amazon famously found that every 100ms of latency cost them 1% in sales. For local businesses, a slow mobile experience means lost phone calls, form submissions, and walk-in visits. Since Google uses mobile-first indexing, your mobile page speed is the metric that matters most -- and it is almost always significantly worse than desktop performance.
Core Web Vitals are three specific metrics that Google considers essential to delivering a great user experience. Largest Contentful Paint (LCP) measures loading performance -- how quickly the largest visible element renders. A good LCP is under 2.5 seconds. Cumulative Layout Shift (CLS) measures visual stability -- how much the page layout shifts unexpectedly during loading. A good CLS score is under 0.1. Interaction to Next Paint (INP), which replaced First Input Delay, measures responsiveness -- how quickly the page responds to user input.
This tool also reports Total Blocking Time (TBT), which correlates with INP and measures how long the main thread is blocked during page load, First Contentful Paint (FCP) for the first visual render, and Speed Index for how quickly content is visually populated. Together these metrics give a complete picture of your page's performance characteristics and where to focus optimization efforts.
Yes. Google confirmed Core Web Vitals as a ranking signal in the 2021 Page Experience update. LCP, CLS, and INP directly influence rankings. Pages that pass all three thresholds get a ranking advantage over slower competitors in the same niche.
A score of 90+ is good (green), 50-89 needs improvement (amber), and below 50 is poor (red). However, individual Core Web Vitals matter more than the composite score. Focus on passing each vital's threshold rather than chasing a perfect overall number.
LCP (Largest Contentful Paint) measures how long the largest visible element takes to render. Good is under 2.5s. Improve it by optimizing images (WebP format, compression), preloading critical resources, reducing server response time, and eliminating render-blocking CSS and JavaScript.
Mobile tests simulate a mid-tier device on throttled 4G, while desktop uses unthrottled broadband with more CPU power. Since Google uses mobile-first indexing, the mobile score matters most for rankings. Prioritize mobile performance optimization.