Core Web Vitals are Google’s measures of real-world page experience. They look at how fast the main content appears, how quickly the page reacts when you tap, and whether things jump around while loading. Good scores make a site feel better to use, and they are a light factor in search.
The three metrics #
- Largest Contentful Paint (LCP) measures how long the biggest visible element, often a hero image or headline, takes to render. Aim for 2.5 seconds or less.
- Interaction to Next Paint (INP) measures how quickly the page responds visually after taps, clicks and key presses. Aim for 200 milliseconds or less.
- Cumulative Layout Shift (CLS) measures unexpected movement of content as the page loads. Aim for 0.1 or less.
These thresholds are the “good” ranges published by Google, and they are judged on the 75th percentile of real visits.
Fixing slow LCP #
- Compress images and serve modern formats such as WebP or AVIF.
- Set explicit width and height, and do not lazy-load the main hero image.
- Use a fast host and a cache so the first byte arrives quickly.
- Remove render-blocking CSS and scripts that the first screen does not need.
- Preload the key font or image when it is critical.
Fixing poor INP #
INP problems usually come from too much JavaScript running on the main thread.
- Remove plugins and third-party scripts you do not use.
- Split long tasks and defer non-critical scripts.
- Avoid heavy work inside click handlers.
Fixing layout shift #
- Always reserve space for images, videos and ads with width and height or an aspect ratio.
- Do not insert banners above content after the page has loaded.
- Use font-display: swap and similar fallback sizing so text does not jump when fonts load.
How to measure #
Use PageSpeed Insights for a quick report that includes real-user data when your site has enough traffic. Google Search Console has a Core Web Vitals report that groups pages that need work. Lighthouse in Chrome DevTools is useful while you are building, but remember that lab tests are not the same as what visitors experience.
Where to start #
Fix the largest problem on your most visited pages first. For many sites that means compressing images, removing unused plugins and reserving space for media. Re-test after each change so you know what worked.
