Largest Contentful Paint (LCP)
A Core Web Vital that measures the time from page load start until the largest visible content element (image, video, or text block) is rendered on screen. Good LCP is 2.5 seconds or less.
LCP captures the user's perception of loading speed by measuring when the main content becomes visible. The largest element is typically a hero image, video thumbnail, or large heading text block. Unlike older metrics like First Contentful Paint, LCP focuses on meaningful content rather than any pixel change.
For engineering teams optimizing LCP, focus on the critical rendering path for your largest element. Common LCP improvements include optimizing hero images (proper sizing, modern formats like WebP/AVIF, preload hints), reducing server response time (TTFB optimization), eliminating render-blocking resources (deferring non-critical CSS and JavaScript), and implementing effective caching strategies. Use Chrome DevTools Performance panel to identify your LCP element and trace the bottleneck. For image-heavy pages, responsive images with srcset and proper width/height attributes prevent unnecessary large downloads. Server-side rendering or static generation significantly improves LCP for JavaScript-heavy applications.
Related Terms
Core Web Vitals
A set of three Google-defined metrics that measure real-world user experience for loading performance, interactivity, and visual stability. Core Web Vitals are a confirmed ranking factor in Google Search.
Interaction to Next Paint (INP)
A Core Web Vital that measures the latency of all user interactions (clicks, taps, keyboard input) throughout the page lifecycle, reporting the worst interaction. Good INP is 200 milliseconds or less.
Cumulative Layout Shift (CLS)
A Core Web Vital that measures the total amount of unexpected layout shifts that occur during a page's entire lifespan. Good CLS is 0.1 or less, where layout shifts are calculated from the impact and distance of moving elements.
Time to First Byte (TTFB)
The duration from the user's request to the first byte of the server response reaching the browser. TTFB measures server-side processing speed and network latency, directly impacting all subsequent loading metrics.
Crawl Budget
The number of pages a search engine bot will crawl on your site within a given timeframe, determined by crawl rate limit and crawl demand. Crawl budget optimization ensures important pages are discovered and indexed efficiently.
Canonical URL
An HTML element that tells search engines which version of a page is the preferred one when multiple URLs serve similar or identical content. Canonical tags consolidate ranking signals and prevent duplicate content issues.