What do LCP, INP and CLS mean?

Q: What do LCP, INP and CLS mean?

LCP measures loading, INP responsiveness and CLS visual stability. Good means 2.5 s or less, 200 ms or less and 0.1 or less, at the 75th percentile.

They are the three Core Web Vitals Google uses to describe a page's user experience. Largest Contentful Paint (LCP) measures loading: how long the main content takes to appear. Interaction to Next Paint (INP) measures responsiveness: how quickly the page reacts when you click, tap or type. Cumulative Layout Shift (CLS) measures visual stability: how much the layout jumps around. Good means LCP within 2.5 seconds, INP within 200 milliseconds and CLS of 0.1 or less.

The three metrics at a glance

Metric	Measures	Good	Needs improvement	Poor
LCP	Loading	2.5 s or less	up to 4 s	over 4 s
INP	Responsiveness	200 ms or less	up to 500 ms	over 500 ms
CLS	Visual stability	0.1 or less	up to 0.25	over 0.25

These are the thresholds in Google's Core Web Vitals report help. A page passes when all three are good at the 75th percentile of visits, measured separately for mobile and desktop.

LCP: Largest Contentful Paint

LCP is the time from the moment someone starts loading the page until the largest image, video or block of text in the visible area has rendered. Eligible elements include <img> elements, images inside SVG, a video's poster or first frame, CSS background images and block-level text. The browser stops looking for new candidates once the visitor interacts. A slow LCP is usually a slow server response, a large or late-discovered hero image, or CSS and scripts that block rendering.

INP: Interaction to Next Paint

INP watches the clicks, taps and key presses during a visit and measures how long each takes until the browser can paint the next frame. Hovering, scrolling and zooming do not count. The reported value is the slowest interaction, ignoring outliers on pages with many interactions. INP replaced First Input Delay (FID) as a Core Web Vital in March 2024; FID looked only at the first interaction, while INP covers the whole visit. Poor INP usually comes from long JavaScript tasks keeping the main thread busy.

CLS: Cumulative Layout Shift

CLS adds up unexpected layout shifts, such as text jumping down when an image or advert loads above it, and reports the largest burst of them during the visit. Each shift is scored by how much of the screen moved and how far. Shifts within 500 milliseconds of a click, tap or key press are excluded, because the visitor expects the page to change then.

Where do the numbers come from?

Search Console's Core Web Vitals report uses field data from the Chrome UX Report: real Chrome visits over the last 28 days, grouped into sets of similar pages, each group rated by its worst metric. Lab tools like Lighthouse load the page without a real visitor, so they cannot measure INP and use Total Blocking Time as a stand-in, as web.dev's overview of Web Vitals explains. Treat lab scores as a way to debug, and field data as the verdict.

Do Core Web Vitals affect rankings?

Google highly recommends achieving good Core Web Vitals for success with Search and says page experience aligns with what its core ranking systems seek to reward. It is not a shortcut: a fast page still needs to be the best answer. How do I fix poor Core Web Vitals scores? covers what to change for each metric.

How AutoPSEO helps

AutoPSEO's Core Web Vitals report reads the Chrome UX Report history for your whole site or a single URL, by phone, desktop or tablet, and charts LCP, INP and CLS (plus first contentful paint and time to first byte) at the 75th percentile over about six months of weekly data, so you can see when a metric started to slip.