How We Measure Website Performance

Full transparency on our methodology, data sources, confidence levels, and limitations.

Core Measurement

Google PageSpeed Insights API

We measure every site's mobile performance using Google's PageSpeed Insights API, which provides real-world performance data from the Chrome User Experience Report (CrUX).

Three Core Web Vitals Metrics:

LCP: Loading speed—target ≤2.5s (75th percentile)
INP: Responsiveness—target ≤200ms (75th percentile)
CLS: Visual stability—target ≤0.1 (75th percentile)

Passing threshold: Sites passing all 3 metrics at 75th percentile are counted as passing Core Web Vitals.

Data Sources & Aggregation

City-Level Aggregation

For each city × industry, we compute:

Average mobile score
Passing rate (% meeting all 3 CWV metrics)
Sample size (number of measured sites)
Confidence level (HIGH ≥1000 | MEDIUM ≥100 | LOW)

National Aggregation

Weighted averages across all cities:

National Avg = Σ(City Avg × City Sample Size) / Σ(City Sample Size)

Confidence Levels

Tier	Sample Size	Meaning
HIGH	n ≥ 1,000	Statistically significant; narrow confidence interval
MEDIUM	100 ≤ n < 1,000	Reasonably reliable; moderate confidence interval
LOW	n < 100	Preliminary; wider confidence interval; use with caution

95% confidence intervals reported for all aggregated metrics.

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