Core Web Vitals Explained for Business Owners: What They Are and How to Pass

If you have ever run your website through a speed test and seen red numbers, you have met Core Web Vitals. They are three measurements Google uses to judge how a page feels to a real person. You do not need to be technical to understand them, and you can often improve them with a handful of changes.

The three metrics in plain language

Google judges each metric at the 75th percentile of real visits, which means three out of four visitors should have at least that good an experience. Interaction to Next Paint replaced an older metric called First Input Delay in 2024.

Lab data versus real-user data

A speed test such as PageSpeed Insights runs your page once on a simulated phone and gives a score from 0 to 100. That is lab data, useful for finding problems. Real-user data comes from Chrome visitors over the previous 28 days and is what Google actually uses. Your site needs enough traffic to have it, so small sites often only see lab results.

How to improve each metric

Largest Contentful Paint

• Compress and resize the main image, and serve it in WebP or AVIF. A 4 MB photo is the usual culprit.
• Do not lazy-load the image at the very top of the page. Load it first.
• Reduce the time your server takes to respond, with caching and a content delivery network.
• Remove render-blocking CSS and scripts from the start of the page.

Interaction to Next Paint

• Send less JavaScript. Remove libraries you do not use and split code by page.
• Delay third-party scripts such as chat widgets and trackers until after the page is usable.
• Break up long tasks so the page can respond between them.

Cumulative Layout Shift

• Set width and height on every image, video and embed so space is reserved.
• Reserve space for banners, ads and cookie notices instead of inserting them above content.
• Load fonts in a way that does not cause text to jump when they arrive.

Does it matter for your business?

Mostly in two ways. A slow page loses visitors who never come back, which means fewer enquiries from the same traffic. And when two pages are otherwise equally relevant, the faster one has an edge in search. Fix the biggest problems first rather than chasing a perfect 100.