Answer
What is LCP (Largest Contentful Paint)?
Last reviewed · WebVitalist
Largest Contentful Paint (LCP) measures loading: how long the largest image or text block in the viewport takes to render. Google classes LCP as good at 2.5 seconds or less and poor above 4 seconds, assessed at the 75th percentile of field data. The usual culprit is a slow hero image or a slow server.
What to do about it
- Find your LCP element. PageSpeed Insights and Chrome DevTools (Lighthouse tab) name the image or text block that counts as your LCP — fix that element first.
- If the LCP element is an image, export it at the size it displays, compress it, and use a modern format such as WebP or AVIF. Do not lazy-load it; it is above the fold.
- Ask your developer to preload the hero image and give it a high fetch priority, so the browser starts downloading it before it has parsed the rest of the HTML.
- If the LCP element is text, cut render-blocking CSS and web fonts: the browser cannot paint the headline until the CSS arrives.
- If LCP is poor in field data but fast in lab tests, suspect the server under real traffic. Check caching and server response time (TTFB).
What WebVitalist checks
The free scan runs 19 technical checks on one public URL. These are the ones that matter for this question:
- Server response time (ttfb): The free scan records how long the server took to deliver the HTML and warns when that took longer than 1,500 ms. A slow first byte is the first thing to rule out when LCP is poor.
- HTML size (html-size): The free scan warns when the HTML document is larger than 400 kB, which the browser must download and parse before it can paint anything.
A paid audit ($9 and up) also runs a real mobile Lighthouse test through Google PageSpeed Insights and reads field data for LCP, INP and CLS, where Google has it.
Free scan
Paste your page URL and see the technical score and top issues in about 30 seconds. No account, no credit card.