methodology / Performance / #34

Core Web Vitals from CrUX (Real User Monitoring)

live factor #34 · Performance · scoring impl: implemented · weight 2.7%

What we measure

Lab tests measure your site once on a synthetic device. CrUX uses real Chrome user data over the last 28 days, which is what Google actually uses for rankings.

How to improve your score

Optimize the same metrics as in lab tests — LCP (largest contentful paint), INP (interaction to next paint), and CLS (cumulative layout shift). Improvements show up in CrUX over a 28-day rolling window, so changes take time to surface.

Data source

Data source for this factor is not yet documented.

Implementation notes

Call the CrUX API by origin, fall back to URL-level if origin data is missing.

Scoring

Scoring formulas are versioned with the methodology. The current method (v1.1.0) maps raw measurements to pass, warn, fail. Factor weights determine how much each contributes to the composite — see the methodology index for the full table.

Version history

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