Largest Contentful Paint
Also known as: LCP
Largest Contentful Paint measures the time until the largest visible element on a page finishes rendering.
In full
Largest Contentful Paint, usually shortened to LCP, records the moment the largest visible element in the viewport finishes rendering, which is typically a hero image, a video poster frame, or a large block of heading text. It is the closest single metric to the question a visitor is actually asking, which is whether anything has appeared yet. Google considers under 2.5 seconds good and over 4 seconds poor, measured at the 75th percentile of real visits. Common causes of a poor score are an oversized hero image, slow server response, render-blocking CSS or JavaScript, and web fonts that hide text while loading.
Why it matters
On most websites, compressing and correctly sizing the largest image accounts for the majority of the available improvement, which makes it unusually good value for the effort.