Read Web Vitals
Use performance measurements to find pages and visitor environments that need attention.
Open Site health, choose the Pixel, then select Vitals. This page shows performance measurements collected after Web Vitals is enabled for that Pixel. See Set up Site health if the page is empty or the switch is off.
Read the overview
- Choose the date range at the top of the page.
- Review the five metric cards. Select one card to show its trend, or select two to compare their trends in the chart.
- Check the distribution below the chart: Good, Needs improvement, and Poor show how the collected measurements are classified.
| Metric | What it helps you check |
|---|---|
| LCP | How quickly the main content becomes visible. |
| CLS | Whether visible content moves unexpectedly while the page loads. |
| INP | How quickly the page responds after an interaction. |
| FCP | When the browser first displays page content. |
| TTFB | How long it takes to receive the first response from the server. |
The cards show the p75 value: 75% of collected measurements are at or below this value. Use it to understand the typical slower experience, rather than relying on a single visit. CLS is shown as a score; the other measurements are shown in milliseconds.
When a card reports fewer than 30 samples, CJM marks its p75 value as less reliable. Collect more visits before making an important decision from that number.
Find the affected segment
Use Breakdown Vitals below the chart to compare the same five measurements by:
- Page
- Device
- Browser
- OS
- Select a breakdown tab.
- Compare the value and rating for each row.
- Use the page controls when there are more rows.
- Note the segment with the poorest or least reliable result, then share that context with the person who manages the website.
For example, a poor result only on one page points to that page first. A result limited to one device or browser is a reason to test the website in that environment. The breakdown helps narrow the investigation; it does not identify the cause or apply a fix.
When measurements are missing
Web Vitals depend on browser support, visitor interactions, and page lifecycle events such as hiding or leaving a page. A page may therefore have some measurements but not all five. Check that Web Vitals is active, use a date range with recent traffic, and allow real visits to accumulate before comparing segments.