Core Web Vitals Field Data
Field data is what Google actually uses to rank your site. It reflects real user experiences across all devices and networks — not controlled lab conditions.
Core Web Vitals field data comes from the Chrome UX Report (CrUX) — a dataset of real user experiences collected by Chrome from opted-in Chrome users. Unlike lab data from tools like Lighthouse or PageSpeed Insights, field data reflects the true distribution of performance across your actual visitors.
Google uses field data, not lab data, for its search ranking signals. The Page Experience update and Core Web Vitals ranking factors are based on the 75th percentile CrUX values for a URL — meaning 75% of your real users must experience 'Good' LCP (under 2.5s) for the page to receive a 'Good' status in Google's systems.
Field data and lab data often disagree. A site might score 90+ in PageSpeed Insights (lab) but have 'Needs Improvement' CrUX field data. This usually means real users have slower devices or network connections than the simulated test conditions, or that personalised content delays the LCP element for certain user segments.
FAQ
What is Core Web Vitals field data?
Field data is Core Web Vitals measurements collected from real users in production via Chrome's browser instrumentation and the CrUX dataset. It reflects actual performance across all devices, networks, and user conditions.
Why does my field data differ from PageSpeed Insights lab scores?
PageSpeed Insights lab scores use a fixed mid-range Android device with 4G throttling. Real users have diverse devices and connections. If your actual users are on slower devices or connections, field data will be worse than lab scores.
How long does CrUX data take to update?
CrUX data is aggregated in a 28-day rolling window. Performance changes take weeks to appear in field data. This is why continuous lab monitoring is important — it detects regressions immediately, while CrUX data lags behind.
How does AuditJet use field data?
AuditJet displays CrUX field data alongside synthetic lab scores for each monitored page. This gives teams both views: the immediate regression detection of lab data and the Google-ranking-relevant 75th percentile from real users.
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