# Largest Contentful Paint (LCP)

> LCP measures how long it takes for the largest image or text block in the viewport to render. A good LCP is 2.5 seconds or less.

**Largest Contentful Paint (LCP)** is the time from when a page starts loading until the largest image, video poster or text block in the viewport is rendered. It is one of the three [Core Web Vitals](/glossary/core-web-vitals) and stands in for "when did the main content appear?".

| Rating | LCP (75th percentile) |
|---|---|
| Good | 2.5 s or less |
| Needs improvement | 2.5 s to 4.0 s |
| Poor | Over 4.0 s |

## Common causes of a slow LCP

- A large hero image that is not compressed, resized or served in a modern format (AVIF or WebP)
- The LCP image is discovered late, for example loaded by JavaScript or as a CSS background
- Lazy-loading the LCP image, which delays it
- A slow server response; see [TTFB](/glossary/ttfb)
- Render-blocking CSS and JavaScript

## How to improve it

Serve the LCP image at the size it is displayed, in AVIF or WebP, and mark it with `fetchpriority="high"` instead of `loading="lazy"`. Preload it if it is not in the initial HTML. Reduce render-blocking resources and speed up the server response.