# CrUX Monitoring



Chrome User Experience Report (CrUX) provides real-world performance data collected from Chrome users who have opted into sharing usage statistics. This is the same data Google uses for search ranking.

## What is CrUX? [#what-is-crux]

CrUX is a public dataset of real user experience data collected by Google Chrome. It includes:

* Core Web Vitals metrics (LCP, CLS, INP)
* Navigation metrics (TTFB, FCP)
* Data from millions of Chrome users worldwide
* 28-day rolling aggregates

<Callout type="info">
  CrUX data is refreshed weekly (Google updates the CrUX History API on Mondays) and represents a rolling 28-day window of user experience.
</Callout>

## Why CrUX Matters [#why-crux-matters]

### Google Search Ranking [#google-search-ranking]

Google uses CrUX data as a ranking factor. Sites with good Core Web Vitals get a ranking boost in search results. CrUX is the definitive source for this evaluation.

### Real User Data [#real-user-data]

Unlike lab tests, CrUX shows actual user experiences:

* Real devices and networks
* Real geographic distribution
* Real user behavior patterns

### Comparison with RUM [#comparison-with-rum]

| Aspect           | CrUX                    | RUM                      |
| ---------------- | ----------------------- | ------------------------ |
| Data source      | Chrome users only       | All visitors with script |
| Update frequency | Weekly                  | Real-time                |
| Coverage         | Chrome desktop + mobile | All browsers             |
| Granularity      | Origin or URL level     | Page-level detail        |
| Historical data  | Public dataset          | Your account data        |

## Using CrUX in VitalSentinel [#using-crux-in-vitalsentinel]

### Adding URLs [#adding-urls]

Navigate to your domain's **CrUX Monitoring** section and click **Manage Pages**. You'll see two tabs:

**Manual tab:**

1. Enter pages in the text area (one per line for bulk import, or a single page)
2. Click **Add page** (or **Add pages** for multiple)

**Sitemap tab:**

1. Shows pages discovered from your sitemap scan
2. Click **Track all sitemap pages** to monitor all discovered pages at once
3. Pages already being monitored are automatically skipped

### URL Data Status [#url-data-status]

Each monitored page shows one of three states, so you can tell at a glance whether CrUX has data for it yet:

| Status                        | Meaning                                                                                              |
| ----------------------------- | ---------------------------------------------------------------------------------------------------- |
| **Data available**            | CrUX has returned aggregated metrics for this page                                                   |
| **No data yet**               | The page has been collected, but Google doesn't have enough Chrome traffic to publish metrics for it |
| **Awaiting first collection** | The page was just added and the next collection cycle hasn't run yet                                 |

Pages showing **No data yet** are still worth keeping if you expect traffic to grow - the moment they cross Google's threshold, metrics start appearing. Pages **Awaiting first collection** usually pick up data after the next weekly collection.

<Callout type="info">
  If no sitemap URLs appear, run a sitemap scan from Domain Settings first.
</Callout>

<Callout type="info">
  The number of CrUX URLs you can monitor depends on your plan.
</Callout>

### Available Metrics [#available-metrics]

For each URL, you'll see:

| Metric | Description               |
| ------ | ------------------------- |
| LCP    | Largest Contentful Paint  |
| CLS    | Cumulative Layout Shift   |
| INP    | Interaction to Next Paint |
| TTFB   | Time to First Byte        |

### Mobile vs Desktop [#mobile-vs-desktop]

CrUX data is broken down by form factor:

* **Mobile** - Phones and small tablets
* **Desktop** - Laptops and desktop computers

Each has separate thresholds and data, as mobile performance typically differs from desktop.

### Percentile Values [#percentile-values]

VitalSentinel displays the &#x2A;*75th percentile (P75)** value for each metric. This means 75% of your users experience this value or better.

The P75 is the industry standard for Core Web Vitals assessment and is what Google uses for search ranking.

### Assessment Status [#assessment-status]

Each metric shows an assessment based on the P75 value:

| Status                | Meaning                          |
| --------------------- | -------------------------------- |
| **Pass**              | P75 meets the "good" threshold   |
| **Fail**              | P75 exceeds the "poor" threshold |
| **Needs Improvement** | P75 is between good and poor     |
| **No Data**           | Insufficient traffic for CrUX    |

### Distribution View [#distribution-view]

The distribution chart shows what percentage of users fall into each category:

* **Green (Good)** - Experiences meeting the threshold
* **Yellow (Needs Improvement)** - Experiences in the middle range
* **Red (Poor)** - Experiences not meeting the threshold

### Trend Indicators [#trend-indicators]

Each metric shows whether performance is:

* **Improving** - Getting better over time
* **Declining** - Getting worse over time
* **Stable** - No significant change

### Detailed Breakdowns [#detailed-breakdowns]

Opening a monitored page reveals deeper CrUX breakdowns beyond the headline metrics:

* **Core Web Vitals trends** over time, per metric
* **Performance and device distribution** across your users
* **Navigation types** (how users arrived at the page)
* **Round-trip time** (network latency to your users)
* **LCP resource types and image subparts** (what the largest element is and where its load time goes)

## CrUX vs Your RUM Data [#crux-vs-your-rum-data]

You might notice differences between CrUX and your RUM data:

### CrUX may differ because: [#crux-may-differ-because]

1. **Chrome only** - CrUX excludes Safari, Firefox, Edge users
2. **Opt-in users** - Only Chrome users who share statistics
3. **28-day aggregate** - Smooths out daily variations
4. **Different sampling** - Google's sampling may differ from yours

### When to use which: [#when-to-use-which]

* **CrUX** - For SEO evaluation and Google ranking assessment
* **RUM** - For detailed debugging and all-browser coverage

## Eligibility for CrUX [#eligibility-for-crux]

Not all URLs have CrUX data. Requirements:

1. **Publicly accessible** - URL must be indexable
2. **Sufficient traffic** - Enough Chrome users visiting
3. **Not blocked** - robots.txt must allow indexing

<Callout type="warn">
  New pages or low-traffic pages may not have CrUX data. Use RUM for immediate insights.
</Callout>

## Origin vs URL Data [#origin-vs-url-data]

CrUX provides two levels of data:

### Origin Level [#origin-level]

Aggregated data for your entire domain (e.g., `https://example.com`), labeled **Whole Site** in the page list.

* Always available if you have any traffic
* Represents overall site health
* Good for monitoring your homepage and main landing pages

### URL Level [#url-level]

Specific page data (e.g., `https://example.com/products/widget`)

* Requires significant traffic to that URL
* More granular insights
* Useful for key pages

## Historical Trends [#historical-trends]

VitalSentinel tracks CrUX data over time:

* Weekly snapshots stored
* Trend charts showing improvement/regression
* Compare current vs previous periods

## Improving CrUX Scores [#improving-crux-scores]

Since CrUX is a 28-day aggregate:

1. **Make improvements** to your site
2. **Wait 4-6 weeks** for data to reflect changes
3. **Monitor RUM** for immediate feedback
4. **Check CrUX** for Google's view

### Priority Order [#priority-order]

Focus on metrics in this order:

1. **LCP** - Biggest impact on user perception
2. **INP** - Critical for interactivity
3. **CLS** - Visual stability

## Related Features [#related-features]

<Cards>
  <Card title="RUM Monitoring" href="/features/rum-monitoring">
    Real-time data from all browsers
  </Card>

  <Card title="Synthetic Monitoring" href="/features/synthetic-monitoring">
    On-demand Lighthouse tests
  </Card>

  <Card title="Google Search Console" href="/features/google-search-console">
    See how CrUX affects your search ranking
  </Card>
</Cards>