Core Web Vitals explained simply: LCP, INP and CLS

Google measures how a website feels for real visitors and sums it up in three metrics: the Core Web Vitals. It sounds technical, but it is easy to understand.

The three values

LCP: how quickly is the most important part visible?

Largest Contentful Paint measures when the largest visible element has loaded, usually the hero image or the main heading. 2.5 seconds or less is good.

INP: how quickly does the page respond?

Interaction to Next Paint measures how long it takes for the page to respond visibly after a tap or click. 200 milliseconds or less is good. INP replaced the older FID metric in March 2024.

CLS: does the page jump around?

Cumulative Layout Shift measures how much content shifts while loading. You know the feeling: you want to tap a link, and suddenly an image slides over it. A value of 0.1 or less is good.

The values and thresholds come from Google (source: web.dev/articles/vitals). A page counts as good if at least 75 percent of page views meet the threshold.

Why it matters to you

Google uses the Core Web Vitals as part of its assessment of page experience (source: developers.google.com/search/docs/appearance/core-web-vitals). Google also states clearly that good content matters more. The direct benefit of fast pages lies elsewhere: visitors leave less often, especially on a phone with a weak connection.

How to check your values

• PageSpeed Insights (pagespeed.web.dev): enter the address, done. At the top you see real user data if your site has enough visitors, below that a lab test.
• Google Search Console: the "Core Web Vitals" report shows which pages are good and which should be improved.
• Lighthouse in Chrome's developer tools (F12) for a quick test in between.

The lab test varies from run to run. Test several times and look at the trend.

Typical causes and solutions

• Poor LCP: usually images that are too large. Solution: deliver images in modern formats like WebP or AVIF and in the right size, and load the hero image with priority.
• Poor INP: too much JavaScript, often from plugins, chat windows or tracking. Solution: remove what is not needed.
• Poor CLS: images without a fixed size, banners or fonts that load late. Solution: specify width and height for images and reserve space for elements that appear later.

Frequently asked questions

My website builder shows poor values. What can I do?

With website builders you have little control over the code. Shrinking images and removing unnecessary elements helps a little. A fundamental change usually only comes with a leaner system.

Do I need 100 points in Lighthouse?

No. The score comes from a lab test. What matters is that the three values are in the green range for real visitors.