Overview
CrUX Monitoring shows the Core Web Vitals that Google publishes for your site and pages, from real Chrome visits, on Phone and Desktop.
CrUX Monitoring shows the speed scores that Google publishes for your site and your pages. Google uses these scores as a search ranking signal, so they show how Google judges the speed of your site.
What CrUX is
CrUX is the Chrome User Experience Report. Google collects it from Chrome users who share usage statistics. It is field data: it comes from real visits on real devices and networks, not from a test.
CrUX Monitoring shows four measures from CrUX:
| Measure | What it shows | Good up to | Poor above |
|---|---|---|---|
| LCP (Largest Contentful Paint) | When the main content appears | 2.5 s | 4 s |
| INP (Interaction to Next Paint) | How fast the page reacts to a click or a tap | 200 ms | 500 ms |
| CLS (Cumulative Layout Shift) | How much the page jumps while it loads | 0.1 | 0.25 |
| TTFB (Time to First Byte) | How fast your server sends the first byte | 800 ms | 1.8 s |
LCP, INP and CLS are the three Core Web Vitals. Google does not use TTFB to judge Core Web Vitals. TTFB is the first thing to check behind a slow LCP.
How Google judges a page
Google rates each measure Good, Needs improvement or Poor. A figure is the value that 3 out of 4 page loads reach or do better than. A device passes Core Web Vitals when LCP, INP and CLS are all Good. Google rates Phone and Desktop separately.
Whole site and one page
CrUX has two levels of data:
- Whole site: the figures for all pages of your site together (the origin, for example
https://example.com). The Pages card shows this row with a Whole site chip. You cannot remove it. - One page: the figures for one address, for example
https://example.com/pricing/. You add these pages yourself.
Google publishes data only for a site or a page with enough Chrome visits. A busy site often has whole-site data, but many of its pages have none. Pages with few visits never get CrUX data.
How often the data updates
Google publishes CrUX data once a week. Each weekly figure covers the 28 days before it. VitalSentinel asks Google for new data automatically, so you do not need to do anything.
Because each figure covers 28 days, a change on your site shows slowly. After you fix a page, the CrUX figures can take some weeks to show the full effect. To see the effect of a fix sooner, use RUM Monitoring.
Google's figures always cover its latest 28 days, whatever dates you select in the filter bar. The dates change only the weekly history in the charts.
Before you start
- CrUX Monitoring needs no script and no connection. VitalSentinel gets the data from Google.
- To open it, select CrUX Monitoring in the Web performance group of the domain sidebar.
- Workspace owners and admins can add and remove pages. Members see the pages read-only.
- The number of pages you can track depends on your plan. See Plans and limits.
The CrUX Monitoring Overview
The Overview shows, from top to bottom:
- The verdict: one sentence that says if your whole site passes Google's Core Web Vitals.
- The Site Health banner, if Site Health Monitoring found CrUX issues.
- The Core Web Vitals card: the weekly history of your whole site.
- The Worth tracking suggestions (owners and admins only).
- The Pages card: every page you track, with Google's latest figures. See Pages.
The filter bar at the bottom of the page holds the date range and the filters of the Pages card. For the filter bar, see Using the app.
The verdict
The verdict at the top of the CrUX Monitoring Overview judges your whole site. It names the device that is nearer to failing. Next to it, the verdict shows the LCP, INP and CLS of that device in their band colors.
| Verdict | Meaning |
|---|---|
| Your site passes Google's Core Web Vitals on Phone (or Desktop) | All three measures are Good, with room to spare. |
| Your site passes Google's Core Web Vitals on Phone, but LCP is close to the limit | The site passes, but one measure is within 10% of its good limit. |
| Your site does not pass Google's Core Web Vitals on Phone | At least one measure is Needs improvement or Poor. |
A measure can be 5% or less over its good limit. Then the ? next to the verdict says that the site fails by a small amount. For example: LCP on Phone: just over the limit.
The measure in the sentence can be LCP, INP or CLS. Hover the ? next to the verdict to see the result for both devices and the good limit of each measure. If a measure dropped out of Good since the week before, the ? says so.
The Core Web Vitals card
The Core Web Vitals card on the CrUX Monitoring Overview shows the whole site week by week. It has one tab for each measure: LCP, INP, CLS and TTFB. Each tab shows the latest Phone and Desktop figures in their band colors.
The chart has one line for Phone and one line for Desktop. The colored bands behind the lines are Google's Good, Needs improvement and Poor ranges. If a measure stays well inside the good range, the chart ends at the good limit. Then the whole chart is the Good zone.
The chip at the top right, for example 72% Phone, shows the share of Chrome visits that come from phones. The card shows one point per week, because Google publishes CrUX weekly.
The date range
The CrUX Monitoring filter bar offers Last 90 days, Last 6 months and Last 12 months. The default is Last 6 months. The shortest range is 90 days, because a shorter range holds too few weekly points. VitalSentinel keeps CrUX data for 16 months on every plan. See Plans and limits.
Page states
No pages added yet
If you track no pages, the CrUX Monitoring Overview shows Add your pages to see how Google rates their speed. Owners and admins click Add pages to start. See Pages.
Google has no CrUX data for your site yet
If Google publishes no data for any page you track, the Overview shows Google has no CrUX data for and the name of your domain, followed by yet. For example: Google has no CrUX data for example.com yet. This is not an error. Google publishes data only for sites with enough Chrome visits. The message says when VitalSentinel last asked Google. VitalSentinel asks again automatically.
The message offers two other ways to measure your speed:
- Open RUM Monitoring (or Install the RUM script): measure the speed of all your own visitors.
- Open Synthetic Monitoring: run lab tests on your pages.
Google has not published whole-site figures yet
If Google has data for some pages but not for the whole site, the Overview shows Google has not published whole-site figures yet. The verdict and the Core Web Vitals card do not show. The Pages card still lists the pages that Google rates.
Under the message, CrUX Monitoring offers See how fast your whole site is for real visitors. Click Open RUM Monitoring, or Install the RUM script if RUM Monitoring is not set up. RUM Monitoring measures the speed of your own visitors, also when Google has no data.
No new CrUX data
Sometimes VitalSentinel gets no new data from Google for some time. Then a banner at the top of CrUX Monitoring says No new CrUX data since and a date (or No new CrUX data lately). Click See why to see the state of the module and what to do.
The pages of CrUX Monitoring
- Pages: the Pages card, the page statuses, and how to add and remove pages.
- Page details: the detail page of one tracked page or of the whole site.
CrUX, RUM and Synthetic Monitoring
| CrUX Monitoring | RUM Monitoring | Synthetic Monitoring | |
|---|---|---|---|
| Source | Google, from Chrome visits | Your own visitors, all browsers | Lab tests on a schedule |
| Setup | None | The RUM script on your site | Add pages to test |
| Updates | Weekly, 28 days per figure | Within minutes | After each test |
| Pages | Only pages with enough Chrome visits | Every page with the script | The pages you add |
| Use it to | See how Google judges your speed | See what visitors get and fix it | Find what to fix, test after a release |
Troubleshooting
Why does CrUX Monitoring show no data for my page?
Google publishes CrUX data only for pages with enough Chrome visits. If a page shows Not enough Chrome visits yet, Google has no data for it. VitalSentinel asks again automatically. If the page never gets enough visits, use RUM Monitoring or Synthetic Monitoring for it.
Why do CrUX figures differ from RUM Monitoring?
CrUX counts only Chrome visits from users who share usage statistics. RUM Monitoring counts all your visitors in all browsers. Each CrUX figure also covers 28 days, so it changes slowly. If the two differ, use CrUX to see how Google judges you, and RUM to find and fix the cause.
Why did my fix not change the CrUX figures?
Each CrUX figure covers 28 days and Google updates it once a week. If you fixed a page recently, wait some weeks before you compare. Check RUM Monitoring to see the effect of the fix sooner.
Why can I not add more pages?
If the Add pages button is disabled, you reached the page limit of your plan. Remove pages that you no longer need, or upgrade your plan. See Billing.
Related
- Pages - add, remove and read your tracked pages
- Page details - the full CrUX history of one page
- RUM Monitoring - the speed of all your own visitors
- Synthetic Monitoring - lab tests on a schedule
- Performance & engagement - if slow pages get fewer Google clicks
- Metrics and thresholds - the limits of every measure
