Largest Contentful Paint (LCP)
A Core Web Vitals metric measuring when the largest content element becomes visible, typically a hero image or heading.
What LCP measures
LCP tracks when the largest visible element renders—usually the hero image, heading, or main content block. This reflects perceived load speed: how quickly visitors feel the page is actually ready. Good LCP is under 2.5 seconds. Above 4 seconds is poor.
Unlike total page load time, LCP focuses on meaningful content. A page can technically "load" quickly but show nothing substantial for seconds—creating terrible perceived performance. LCP captures this user-centric reality.
Why LCP matters for business
Google uses LCP as a ranking factor through Core Web Vitals. Sites with poor LCP rank lower, regardless of content quality. This directly impacts visibility and traffic.
More importantly, LCP correlates strongly with conversion rates. Every additional second of LCP reduces conversions significantly. Visitors don't wait—they bounce to faster competitors.
Common LCP bottlenecks
Unoptimised images: Massive hero images are the most common LCP killer. A 5MB hero takes ages to download on mobile connections. Image optimisation and modern formats like WebP dramatically improve LCP.
Slow server response: If your server takes 2 seconds to start sending content, LCP can't be better than 2 seconds. Edge hosting reduces this to under 100ms by serving from nearby locations.
Render-blocking resources: CSS and JavaScript in the <head> must download before rendering starts. Defer non-critical scripts, inline critical CSS, and eliminate blocking requests above the fold.
Improving LCP
Prioritise above-the-fold content. Preload critical assets like hero images. Use appropriate lazy loading—never on LCP elements. Optimise and compress all images.
Every Fernside site targets sub-2.5s LCP through Astro's static generation, Cloudflare Pages edge distribution, and optimised assets. Good LCP isn't optional—it's standard.
Related terms
Why it matters
Understanding “Largest Contentful Paint (LCP)” helps you speak the same language as our design and development team. If you need help applying it to your project, book a Fernside call.