LCP stands for Largest Contentful Paint, and it’s a key performance metric in Google’s Core Web Vitals framework. LCP measures the time it takes for the largest visible element on a webpage to fully render within the viewport (the part of the page visible to the user) after a user starts loading the page.
Why is LCP important?
LCP focuses on user experience, specifically on how quickly a webpage feels ready and useful to the user. If the largest element (e.g., a hero image, headline, or block of text) loads quickly, the user perceives the page as loading fast—even if other elements are still loading in the background. A poor LCP score can frustrate users, increasing bounce rates and harming engagement.
Google uses LCP as part of its page experience ranking factors, meaning it directly influences how well your site ranks in search results.
What contributes to LCP?
The “largest contentful” element can vary depending on the page, but it’s typically one of the following:
- Images: Hero images, banners, or large featured graphics.
- Videos: Background videos or embedded media.
- Text elements: Large headings, titles, or blocks of visible text.
Good LCP Thresholds
Google defines LCP performance as:
- Good: Under 2.5 seconds
- Needs Improvement: Between 2.5 and 4 seconds
- Poor: Over 4 seconds
Common Causes of Poor LCP
- Slow Server Response Times:
- If your server takes too long to deliver the page content, LCP will be delayed.
- Solutions: Use a faster hosting provider, enable caching, and optimise server performance.
- Render-Blocking Resources:
- CSS and JavaScript files can block the rendering of the largest visible element.
- Solutions: Minify CSS/JS, defer or async load JavaScript, and inline critical CSS.
- Slow Loading Images:
- Large or unoptimised images are a frequent culprit for slow LCP scores.
- Solutions: Use optimised image formats like WebP, enable lazy loading, and serve images via a CDN.
- Client-Side Rendering:
- Pages that rely heavily on JavaScript to render content can delay LCP.
- Solutions: Minimise JavaScript and prioritise server-side rendering or hydration.
- Font Loading Issues:
- Custom fonts can delay text rendering, impacting LCP.
- Solutions: Use font-display: swap in your CSS to load fallback fonts first.
How to Measure and Improve LCP
You can measure LCP using tools like:
- Google PageSpeed Insights: Provides an LCP score with specific recommendations.
- Chrome DevTools: Tracks LCP during a performance audit.
- Lighthouse Reports: Offers an overview of Core Web Vitals, including LCP.
- Google Search Console: Highlights LCP issues site-wide under “Core Web Vitals.”
Improving LCP ensures your site feels faster to users and meets Google’s performance expectations, contributing to both better UX and higher search rankings.
