What is Website Performance Score?
A website benchmark evaluates your site across page load speed, Core Web Vitals, mobile responsiveness, and conversion rate.
The Formula
Score = (ฮฃ Category Scores รท Number of Categories) ร 100
Worked Example
A business website: 2.8s load time, LCP 2.1s, mobile score 72/100, 2.4% conversion rate.
- Load time: 2.5/2.8 = 89/100 (lower is better)
- LCP: 2.5/2.1 = 84/100 (lower is better)
- Mobile: 72/90 target = 80/100
- Conversion: 2.4/3.0 target = 80/100
- Overall = (89 + 84 + 80 + 80) รท 400 ร 100 = 83%
๐ The website scores 83%, good speed but mobile optimization and conversion rate need attention.
Why This Matters
SEO rankings
Core Web Vitals are a Google ranking factor. Sites passing all three metrics rank 24% higher on average.
Revenue impact
Every 100ms improvement in load time increases conversion by 1.11%. Speed directly equals revenue.
User experience
53% of mobile users abandon sites taking over 3 seconds. Speed is the foundation of user experience.
Common Mistakes
โ Testing only on fast connections
Test on 3G/4G connections that your real users experience. Desktop fibre results are misleading.
โ Ignoring Cumulative Layout Shift
CLS causes buttons to jump as the page loads, leading to accidental clicks and user frustration.
โ Not measuring real user data
Lab tests differ from real-world performance. Use field data from Chrome UX Report for accurate benchmarks.
Industry Benchmarks
| Category | Good | Average | Poor |
|---|---|---|---|
| LCP | Under 2.5s | 2.5-4.0s | Above 4.0s |
| Mobile Score | 90+ | 50-90 | Below 50 |
| Conversion Rate | 3%+ | 1.5-3% | Below 1% |
Source: Google Core Web Vitals Report 2025
Benchmark data sourced from Google Core Web Vitals Report 2025.