What the three metrics measure
LCP (Largest Contentful Paint) measures when the largest visible element of a page has loaded, usually a large image or the main heading. For visitors, this is the moment the page is “there”. Good is 2.5 seconds or less.
INP (Interaction to Next Paint) measures how quickly a page responds to input, for example a tap on the menu or a button. It measures the time until the visible response. Good is 200 milliseconds or less. INP replaced the earlier metric FID in March 2024.
CLS (Cumulative Layout Shift) measures how much content shifts unexpectedly during loading. If a button jumps away just as someone is about to tap it, the score goes up. Good is a score of 0.1 or less.
How Google evaluates the scores
Google evaluates data from real visits with the Chrome browser, separately for smartphone and desktop. A page meets the thresholds if at least 75 percent of visits stay within them.
The Core Web Vitals are one signal among many: relevant, helpful content counts for more. But between similarly good pages, the better user experience can tip the balance. And regardless of ranking, fast pages lose fewer visitors before they have read anything at all.
How to check your website
- PageSpeed Insights: enter an address and you will see the scores from real visits, provided your page has enough visitors, plus a lab test with specific recommendations.
- Google Search Console: the “Core Web Vitals” report summarizes all pages of a website and shows which groups of pages have problems.
- Browser developer tools: for professionals who want to investigate individual causes in detail.
Typical causes and what helps
- Slow LCP: images that are too large at the top of the page, a slow server or many scripts that load before the actual content. Modern image formats such as WebP or AVIF in the right size, fast hosting and a lean structure help.
- Poor INP: too much JavaScript, often from plugins, tracking scripts or embedded chat windows. Removing unnecessary scripts and loading the rest only when needed helps.
- High CLS: images without a fixed width and height, banners that appear later or fonts that switch during loading. Reserving space for all elements from the start helps.
An example
Suppose a practice website shows a team photo at the top in full camera resolution, several megabytes in size. On a smartphone, it only appears after four seconds, and as soon as it does, the “Book an appointment” button slides down. With a compressed image in the right size and fixed dimensions, the page is visible in well under 2.5 seconds, and nothing jumps around anymore.
Good scores from the start
With a new website or a relaunch, good scores can be planned in: images in the right size, few scripts, reserved space for all elements and fast hosting. For existing websites, checking the scores is part of regular maintenance, because new plugins, images or embedded services can worsen them at any time.