Docs » Manage synthetic tests » Compare run results to Web Vitals with Splunk RUM

Compare run results to Web Vitals with Splunk RUM πŸ”—

Splunk Synthetic Monitoring automatically collects Web Vitals for Browser tests. If you also want to measure Web Vital metrics against your run results, then integrate Splunk Synthetic Monitoring with Splunk RUM. Web Vitals capture key metrics that affect user experience and assess the overall performance of your site. Many businesses rely on search engines for users to discover their sites. Google uses Web Vitals to determine page ranking.

Metric name


Largest contentful paint (LCP)

Measures loading performance by capturing the render time of the largest image or text block visible within the viewport.

Cumulative layout shift (CLS)

Measures visual stability by capturing the sum of all individual layout shift scores for every unexpected layout shift that occurs during the entire lifespan of the page. A layout shift occurs any time a visible element changes its position from one rendered frame to the next. Fewer shifts are better for page stability.

First input delay (FID)

Measures the time from when a user first interacts with a web page to the time when the browser responds to that interaction.

Total blocking time (TBT)

Measures the time it takes a page to become interactive and responsive for a user. TBT is collected from a synthetic test, while FID is collected from real user data. They are considered equivalent to each other because they measure the same metric.

Prerequisites πŸ”—

To measure Web Vital metrics against your run results, you need to instrument your browser application with Splunk RUM. See, Instrument browser-based web applications for Splunk RUM.

Compare Web Vitals for your run results πŸ”—

Follow these steps to compare run results to Web Vitals. Web Vitals are a great way of measuring if your tests are actually capturing the performance you expect, such as if you want to compare the latency of your tests by run location. Open the run results of your test.

  1. In Splunk Synthetic Monitoring, navigate to the run results page for the test you’re interested in monitoring. The metrics panel for each run result lists Web Vitals, performance timing, and other metrics. Each Web Vital shows how your metrics compare to the acceptable range.

  • Good: < 100 ms

  • Improve: 100 ms - 300 ms

  • Poor: > 300 ms

  1. Select the flashlight icon to open the sessions in Tag Spotlight.

  2. Review the visits count to find the number of users and synthetic tests that have interacted with the normalized URL specified in the test.

  3. To compare latency of a test by run location, select the filter icon to change the location.

Shows how to toggle among four location options: global, country, region, city.

See also πŸ”—

This page was last updated on Oct 31, 2023.