TL;DR: To analyze Core Web Vitals by device and country, start with Google Search Console to compare mobile and desktop performance, then use CrUX BigQuery for country-level and country-plus-device analysis. Compare LCP, INP, and CLS at the 75th percentile, focus on countries and devices with meaningful data, and use PageSpeed Insights, Lighthouse, or DevTools to investigate the likely causes.
A website can pass its overall Core Web Vitals assessment while delivering a noticeably slower experience to certain users. Mobile visitors may have a higher LCP than desktop users, while visitors in a particular country may experience slower loading because of network latency or infrastructure differences.
That is why looking at Core Web Vitals by device and country matters. Segmenting real-user data shows where performance problems are concentrated instead of hiding them behind a single sitewide number.
Understanding Core Web Vitals by Device and Country
To analyze performance differences, segment real-user Core Web Vitals data by device and country, compare LCP, INP, and CLS at the 75th percentile, and then investigate the segments with the largest gaps.
| Step | What to do | Best source |
|---|---|---|
| 1. Compare devices | Check mobile, desktop, and tablet performance separately. | Search Console, CrUX |
| 2. Compare countries | Identify regions with noticeably different Core Web Vitals results. | CrUX BigQuery |
| 3. Combine both | Compare country + device to find the specific user segments affected. | CrUX BigQuery |
| 4. Find the weak metric | Check whether LCP, INP, or CLS is driving the performance gap. | CrUX, Search Console |
| 5. Investigate the cause | Check TTFB, images, JavaScript, CSS, and rendering for the affected segment. | PageSpeed Insights, Lighthouse, DevTools |
| 6. Prioritize fixes | Fix the largest performance gap affecting a meaningful share of users, then monitor field data. | CrUX, Search Console |
In short: use field data to identify where performance differs, segment it by device and country, and use lab diagnostics to investigate why.
What Are Core Web Vitals?
Core Web Vitals are Google’s user-focused performance metrics covering loading, responsiveness, and visual stability. The current metrics are:
| Metric | What it measures | Good threshold |
|---|---|---|
| LCP | Loading performance | ≤ 2.5s |
| INP | Interaction responsiveness | ≤ 200ms |
| CLS | Visual stability | ≤ 0.1 |
Google recommends evaluating these metrics at the 75th percentile, segmented by mobile and desktop. A page needs to meet the recommended threshold for all three metrics to provide a good Core Web Vitals experience.
This matters because averages can hide poor experiences. If your average LCP is 2 seconds but a meaningful portion of users experience much slower loading, the average does not tell the complete story.
Why Analyze Core Web Vitals by Device and Country?
Looking only at an overall score can make a performance problem appear smaller than it really is.
Core Web Vitals by device
Mobile and desktop users do not load websites under identical conditions. Phones can have less processing power, different viewport sizes, different network conditions, and different interaction patterns.
For example:
| Device | LCP | INP | CLS | Interpretation |
|---|---|---|---|---|
| Desktop | 2.1s | 145ms | 0.04 | Good |
| Mobile | 3.3s | 270ms | 0.08 | Needs investigation |
| Tablet | 2.5s | 185ms | 0.05 | Borderline |
This Core Web Vitals performance by device analysis immediately shows that a sitewide optimization may not solve the main problem. If desktop performance is already healthy but mobile LCP and INP are poor, the next investigation should focus on the mobile experience.
For example, heavy JavaScript can be particularly noticeable on less powerful devices. Large images can also have a greater impact when users are downloading them over slower connections.
Core Web Vitals by country
Geography introduces another layer. A visitor located far from your origin server may experience additional network latency. CDN coverage, routing, connection quality, infrastructure, and the geographic distribution of your traffic can all contribute to differences in Core Web Vitals performance by country.
This is especially important for international ecommerce sites. A global Core Web Vitals score might look healthy while one important market consistently experiences slower pages.
How to Check Core Web Vitals by Device
Google Search Console is a useful starting point for Core Web Vitals by device.
Open the Core Web Vitals report and compare the mobile and desktop views. Search Console groups URLs with similar issues, which can help identify whether a performance problem is isolated or associated with a broader page template.
Pay attention to patterns such as:
- Mobile pages failing while desktop pages pass.
- Several templates showing poor LCP.
- INP problems appear primarily on interactive pages.
- CLS issues affecting pages with dynamic content, banners, or media.
For deeper Core Web Vitals data by device, CrUX provides real-user information by form factor, including phone, tablet, and desktop. This gives you more detailed device segmentation than the mobile and desktop views available in Search Console and helps show which device experiences are contributing to the result.
How to Analyze Core Web Vitals by Country
For Core Web Vitals by country, CrUX is particularly valuable. Its BigQuery dataset provides country-level data that can also be segmented by device, allowing you to compare real-user performance across specific markets and form factors.
For a more detailed comparison, you can use CrUX BigQuery to look at each country alongside its phone, tablet, and desktop results.
A practical analysis is:
- Select your site’s origin and the latest relevant CrUX dataset.
- Compare the countries that represent meaningful portions of your traffic.
- Break those countries down by phone, tablet, and desktop.
- Compare LCP, INP, and CLS separately at the 75th percentile.
- Investigate the segments with the largest performance gaps.
This lets you move beyond a global score and identify whether a problem is geographic, device-specific, or a combination of both.
Search Console is best for identifying affected URL groups by device, while CrUX BigQuery is better suited to detailed Core Web Vitals data by country and device. PageSpeed Insights and Lighthouse are then useful for investigating potential technical causes.
Example of country-level analysis
Imagine your global mobile LCP is 2.4 seconds:
| Country | Mobile LCP | What it suggests |
|---|---|---|
| United States | 2.1s | Healthy |
| United Kingdom | 2.3s | Healthy |
| India | 3.0s | Investigate |
| Australia | 2.8s | Investigate |
You should not immediately conclude that the website’s code is slower in India or Australia. The difference could be related to TTFB, CDN coverage, connection quality, device mix, or the types of pages users access.
The country-level result tells you where to investigate, not necessarily what to fix. Combine it with device-level data and technical diagnostics before making an optimization decision.
Which Tools Show Core Web Vitals by Country?
Not every Core Web Vitals tool provides the same level of segmentation. Search Console is useful for identifying mobile and desktop performance issues, but it is not a country-level Core Web Vitals reporting tool.
For geographic analysis, Chrome UX Report (CrUX) is the more useful source. Its BigQuery dataset includes a country_summary table with aggregated performance data by month, origin, country, and device. This allows you to compare countries and then narrow the analysis to specific device types.
A practical toolset looks like this:
| Tool | Device analysis | Country analysis | Best use |
|---|---|---|---|
| Google Search Console | Yes | No | Find affected URL groups and device-level issues |
| PageSpeed Insights | Test conditions | No geographic segmentation | Diagnose individual pages |
| CrUX | Yes | Not available through the CrUX APIs | Understand real-user performance |
| CrUX BigQuery | Yes | Yes | Detailed country + device analysis |
| Lighthouse | Simulated device | No | Diagnose technical causes |
This distinction prevents a common mistake: trying to use a single performance tool to answer questions it was not designed to answer.
How to Combine Device and Country Data
The most useful Core Web Vitals analysis happens when you combine both dimensions.
Suppose mobile users in India have an LCP of 3.4 seconds and INP of 290ms, while desktop users in the same country pass. That points toward a problem concentrated among mobile users in India, rather than a country-wide performance issue.
From there, investigate network conditions, server response time, image delivery, JavaScript execution, and CDN behavior. The goal is to connect the affected segment with the specific metric and then investigate its likely technical cause.
Use Field Data and Lab Data for Different Jobs
A common mistake is using one performance tool to answer every question. Field data and lab data have different purposes.
Field data represents real users and is therefore useful for understanding actual performance across devices and locations. CrUX is particularly useful for this type of analysis.
Lab data, such as Lighthouse or PageSpeed Insights testing, runs under controlled conditions. It helps diagnose potential causes.
For example, suppose CrUX shows poor mobile LCP in one country. A lab test can then help investigate whether the page has:
- A slow server response time.
- A large LCP image.
- Render-blocking CSS or JavaScript.
- Delayed LCP resource discovery.
- Excessive JavaScript execution.
- Third-party scripts delaying rendering.
This distinction is important. A lab score is not a substitute for understanding how real users experience the site.
What Causes Core Web Vitals to Vary by Country?
A difference in country-level performance does not automatically mean the website has different code for different countries. Several factors can contribute.
Network latency
The physical and network distance between visitors and your infrastructure can increase the time required to retrieve resources.
This can be particularly important for LCP because the browser needs to receive and process the resources required to display the main content.
CDN coverage and configuration
A properly configured CDN can bring cached resources closer to users and reduce network distance.
For international websites, reviewing CDN behavior is therefore an important part of website performance by country. A content delivery network (CDN) can help distribute static resources geographically, although CDN configuration and cache behavior still need to be evaluated.
Device mix
Different countries can have different proportions of phone, tablet, and desktop traffic. A market with a larger share of lower-powered mobile devices may naturally show different performance characteristics.
Connection quality
Real-world connection conditions vary. CrUX provides dimensions that can help put performance results into context, rather than treating every country as if users had identical network conditions.
Server response time
A slow origin can affect visitors regardless of location, but the effect can become more noticeable for geographically distributed audiences.
If high LCP remains after image optimization, investigate the other stages of the loading process as well. Issues such as TTFB, render-blocking resources, JavaScript, and delayed resource discovery can all contribute to LCP.
How to Interpret the Results
Finding a performance gap is only the first step. The next question is whether the pattern points to a device-specific problem, a geographic problem, or an issue affecting both.
| Finding | What it may indicate | What to investigate |
|---|---|---|
| Mobile LCP is poor across all countries | Mobile loading issue | Images, JavaScript, CSS, server response |
| Desktop passes, but mobile fails | Device-specific performance issue | CPU usage, JavaScript, page weight |
| One country is slow on both mobile and desktop | Geographic delivery issue | TTFB, CDN, routing, infrastructure |
| One country is slow only on mobile | Country + device interaction | Device mix, network conditions, mobile resources |
| INP is poor across devices | Responsiveness problem | Long tasks, JavaScript, third-party scripts |
| CLS is poor in one template | Layout implementation issue | Images, fonts, ads, dynamic content |
These patterns are not definitive diagnoses, but they help narrow the investigation. The more dimensions that point to the same problem, the more confidently you can prioritize that area for testing.
How to Turn the Data Into an Optimization Plan
Once you have Core Web Vitals data by country and device, avoid trying to fix every issue simultaneously. Start with the largest meaningful performance gap, especially when it affects a substantial or strategically important portion of your audience.
For example, if desktop users pass across most countries but mobile users consistently have poor LCP, prioritize mobile loading performance.
Then determine what is actually causing the delay.
If LCP is the problem, investigate the LCP element, server response, resource discovery, image delivery, CSS, and rendering. If INP is poor, focus more heavily on JavaScript execution and long tasks. If CLS is the issue, examine images without dimensions, dynamically inserted content, ads, fonts, and other layout changes.
The important point is to connect the segment with the metric, then validate the likely cause with technical diagnostics. Avoid making major changes based on a single country or device result, especially when the affected segment has limited real-user data.
A Practical Workflow for International Websites
A reliable Core Web Vitals analysis can follow four stages: baseline, segment, diagnose, and validate.
1. Establish the baseline.
Start with the overall LCP, INP, and CLS results. Identify which metric is causing the largest performance problem.
2. Segment the data.
Compare mobile, desktop, and tablet performance. Then compare the countries that represent meaningful portions of your audience. Finally, combine country and device data to find concentrated problem areas.
3. Diagnose the cause.
Use PageSpeed Insights, Lighthouse, Chrome DevTools, and server or CDN data to investigate the technical cause. For example, poor LCP may require investigation into TTFB, image delivery, CSS, JavaScript, or resource discovery.
4. Validate the improvement.
After making a change, test it in a lab environment first, then monitor field data to determine whether real users experience the improvement. Field data represents users over a collection period, so a change will not necessarily appear in the data immediately after deployment.
This approach keeps performance optimization focused on measurable user problems rather than isolated PageSpeed scores.
Conclusion
Core Web Vitals by device and country gives you a more useful view of website performance than a single sitewide score. It shows whether problems are concentrated among mobile users, desktop visitors, specific countries, or particular combinations of both.
Start with Search Console for device-level visibility, use CrUX for real-user geographic analysis, and combine the findings with lab diagnostics to investigate the underlying causes.
The goal is not simply to find the country or device with the lowest score. It is to understand why that audience experiences slower loading, weaker responsiveness, or greater instability, and then prioritize the technical changes most likely to improve their real-world experience.
FAQs
How can I check Core Web Vitals by device?
Can Core Web Vitals be measured by country?
What is the best tool for Core Web Vitals by country?
Why are Core Web Vitals worse in one country?
Should I prioritize mobile or desktop Core Web Vitals?
Why does my PageSpeed score look good when Core Web Vitals are poor?
About the Author
