Websites
Website Speed in Plain Terms: What Core Web Vitals Measure
Core Web Vitals are three measurements used to judge how a page feels to real visitors. You don't need to be a developer to understand them, and they're useful when you're checking a developer's work.
The three numbers
| Metric | What it measures | Good result |
|---|---|---|
| LCP | How long the main content takes to appear | Under 2.5 seconds |
| INP | How quickly the page responds to a tap or click | Under 200 milliseconds |
| CLS | How much the layout jumps while loading | Under 0.1 |
These are measured on real visits, at the 75th percentile. So at least three out of four page visits need to meet each target. A single good test on your office Wi-Fi doesn't prove much.
What usually slows a site down
- Large images uploaded straight from a camera or design tool.
- Page builders and plugins that load code on every page, needed or not.
- Too many third-party scripts, such as chat widgets and tracking tags.
- Distant or overloaded hosting, especially if your customers are in another country.
Why international sites need extra care
If your server is in one region and your customers are in the US, UK and Gulf, every request travels a long way. A content delivery network keeps copies of your files close to visitors, which cuts that distance.
What to ask your developer
- What are the mobile scores, not only the desktop ones?
- How large is the home page in total?
- Which third-party scripts load, and are all of them needed?
- Is a CDN in place for visitors in other countries?