Lighthouse 90+ Score Guide

Google's Lighthouse is a free tool that measures the technical quality of your website. It scores across four dimensions: Performance, Accessibility, Best Practices, and SEO. 90+ score is a direct ranking factor for Google.

Why 90+ Score?

Core Web Vitals have been an official ranking factor since 2021. 80-89 is still "good" but 90+ is "excellent" — and Google noticeably rewards this difference.

"A fast site is one that doesn't lose customers."

1. Performance (The Hardest)

Optimize Images

Modern formats (WebP, AVIF) — 30% smaller than JPEG
Right sizing (800px is enough for mobile)
loading="lazy" attribute
fetchpriority="high" for hero images

Reduce JavaScript

Modern sites load 500KB JS on average — unacceptable. Target: under 150KB.

Drop frameworks you don't use (is jQuery still needed?)
Use code splitting (automatic with Next.js)
Load third-party scripts with async or defer

Inline Critical CSS

Inline the CSS needed for first render in <head>. Defer the rest.

Font Strategy

font-display: swap
Only load weights you use (3 weights is enough)
Self-host (not from Google Fonts)

2. Accessibility

alt attribute on all images
label on form inputs
Color contrast (4.5:1 minimum)
Keyboard navigation must work
aria-hidden="true" on decorative SVGs
focus-visible styles

3. Best Practices

HTTPS required
No console errors
Don't use deprecated APIs
Correct image aspect-ratio
Modern Content Security Policy

4. SEO

Title tag (under 60 chars)
Meta description (under 155 chars)
Mobile viewport meta
Correct lang attribute
Indexability (robots.txt, no noindex)
Structured data (Schema.org)

Quick Wins — What You Can Do Today

Convert images to WebP: Use squoosh.app in minutes.
Apply lazy load: loading="lazy" on all img tags.
Defer third-party scripts: Analytics, chat widgets.
Reduce render-blocking CSS: Defer non-critical CSS.
Enable Cloudflare CDN: Free, instant 30% speedup.

Measurement

Monitor Lighthouse continuously:

PageSpeed Insights: One-click test
Search Console: Real user data (CrUX)
Lighthouse CI: Automatic test per deploy

Common Mistakes

Only testing desktop: Mobile score is usually 15-20 points lower.
Measure once, abandon: Score declines over time; monthly measurement essential.
Defending third-party scripts: Most are unnecessary or replaceable.
Saying "we'll optimize later": Performance isn't added later — designed in.

Conclusion

Getting a 90+ score isn't hard — it's hard without continuous monitoring. With the right infrastructure, image optimization, low JavaScript, and right CSS strategy, most sites can reach 90+.

To analyze your site's performance, request a free audit or check our web design service — every site we deliver has 90+ score guaranteed.

How to Get Lighthouse 90+ Score? Complete Guide