PERFORMANCE

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Lighthouse

/ˈlaɪthaʊs/n.

Filed underPerformanceDevopsSEO

In brief · quick answer

An open-source Google auditing tool measuring performance, accessibility, SEO, best practices, and PWA readiness. Produces lab-based scores, not field data.

§ 1 Definition

Lighthouse generates a 0-100 score across five categories. The Performance score is a weighted composite of lab metrics (FCP, LCP, TBT, CLS, Speed Index). It simulates a Moto G4 on a throttled network. A 100 Lighthouse score does not guarantee good Core Web Vitals in the field.

§ 2 How It Works

Runs a controlled simulation on a Moto G4 with throttled network. The performance score uses a log-normal distribution. Provides actionable recommendations.

§ 3 Common Misunderstandings

Lighthouse scores are NOT real-user metrics. They are lab benchmarks. A site can score 100 in Lighthouse but fail CWV for real users. Use Lighthouse for CI regression detection, not as a performance SLA.

§ 4 When to Use

In CI/CD pipelines to catch regressions. For reproducible debugging. In Chrome DevTools for iteration. Always validate with CrUX data.

§ 5 Note

Scores are not comparable across major versions. Always use the latest version.

§ 6 In code

npx lighthouse https://example.com --view --preset=desktop

§ 7 Common questions

Q. Can I pass Lighthouse but fail CWV?: A. Absolutely. Lab vs field data often disagree.
Q. Does Lighthouse measure INP?: A. No. It reports TBT (Total Blocking Time), which correlates with INP.

Key takeaways

Lab auditing tool, not field measurement.
High score does not guarantee good CWV.
Best use: CI regression detection.
Always complement with CrUX or RUM.

How Atomic Glue helps

Atomic Glue uses Lighthouse for CI regression testing and diagnostic debugging. Get in touch.

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# Lighthouse

An open-source Google auditing tool measuring performance, accessibility, SEO, best practices, and PWA readiness. Produces lab-based scores, not field data.

Category: Performance (also: Devops, SEO)

Author: Atomic Glue Performance Team

## Definition

## How It Works

Runs a controlled simulation on a Moto G4 with throttled network. The performance score uses a log-normal distribution. Provides actionable recommendations.

## Common Misunderstandings

## When to Use

In CI/CD pipelines to catch regressions. For reproducible debugging. In Chrome DevTools for iteration. Always validate with CrUX data.

## Note

Scores are not comparable across major versions. Always use the latest version.

## In code

npx lighthouse https://example.com --view --preset=desktop

## Common questions

Q: Can I pass Lighthouse but fail CWV?

A: Absolutely. Lab vs field data often disagree.

Q: Does Lighthouse measure INP?

A: No. It reports TBT (Total Blocking Time), which correlates with INP.

## Key takeaways

Lab auditing tool, not field measurement.
High score does not guarantee good CWV.
Best use: CI regression detection.
Always complement with CrUX or RUM.

## Related entries

Last updated July 2026. Permalink: atomicglue.co/glossary/lighthouse