Core Web Vitals explained in plain English, and how to improve them
Core Web Vitals measure how fast a page loads, how quickly it responds and how stable it is. Here is what each one means, the targets, and the usual fixes.
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Put this into practice
What are Core Web Vitals?
Core Web Vitals are three measures Google uses to describe real-world page experience. Test them on mobile first, because phones are slower and Google mostly judges the mobile version.
The three measures
- Largest Contentful Paint (LCP): how long the main content takes to appear. Aim for 2.5 seconds or less
- Interaction to Next Paint (INP): how quickly the page reacts when someone taps or clicks. Aim for 200 milliseconds or less
- Cumulative Layout Shift (CLS): how much the page jumps around while loading. Aim for 0.1 or less
The usual fixes
- Compress images and use modern formats, and set their width and height so the layout does not jump
- Remove or delay scripts you do not need, especially third-party widgets
- Use caching and a content delivery network so pages are served from close to the visitor
- Reserve space for ads, banners and embeds before they load
How should you read your results?
A lab test is a single run under set conditions. Real-user data, when your page has enough visitors, shows what people actually experience. Run the test two or three times and look at the pattern, not one number.
Frequently asked questions
Do Core Web Vitals decide my ranking?
They are one of many signals. Great content that is slow can still rank, but a slow page also costs you visitors who leave.
Why does my score change between tests?
Server load, network conditions and third-party scripts vary from run to run.