How to Get a Good SEO Score: What Lighthouse Measures and What Google Actually Uses

“I want a 100 on Google” is what we hear most. It's an understandable goal, but it mixes together three different things: your Lighthouse score, the real Core Web Vitals of your visitors and your position in the results. Understanding the difference saves you money and frustration.

Lighthouse is not Google

Lighthouse is an auditing tool (built into Chrome and PageSpeed Insights) that simulates a visit and scores four areas from 0 to 100: performance, accessibility, best practices and SEO. It's a lab test, useful for spotting problems. But the SEO category score only checks the basics: that there's a title and a meta description, that the page can be crawled, that links have text, that images have alt text, among others. Scoring 100 there means “the basics are fine”, not “you'll rank first”.

What Google does use: real Core Web Vitals

Google measures the experience of real people using Chrome. It evaluates three metrics, at the 75th percentile of visits:

• LCP (Largest Contentful Paint): how long it takes for the main content to appear. Good: 2.5 seconds or less.
• INP (Interaction to Next Paint): how quickly the page responds when someone taps or clicks. Good: 200 milliseconds or less. It replaced FID in March 2024.
• CLS (Cumulative Layout Shift): how much the layout “moves” while loading. Good: 0.1 or less.

You can see your real-world data in PageSpeed Insights (the “Discover what your real users are experiencing” section) and in the Core Web Vitals report in Search Console.

What moves the SEO needle, in order of impact

1. Content that answers what people are searching for. One page per search intent, written clearly and with information others don't have.
2. Making sure Google can crawl and index you: a correct sitemap, no accidental blocks in robots.txt or noindex tags, consistent canonical URLs.
3. Meaningful titles and headings: a unique title per page (about 60 characters fit), an appealing meta description (around 155) and a single H1 that says what the page is about.
4. Internal links: connect your pages to each other with descriptive text, not “click here”.
5. Authority: mentions and links from other trusted sites, reviews, a consistent presence in directories.
6. Technical experience: speed, mobile version and accessibility.

How to improve speed without becoming technical

• Images in modern formats (AVIF or WebP), with width and height defined to avoid layout jumps (CLS).
• Lazy-load images that sit below the first screen; the main image, on the other hand, should load with priority.
• Self-hosted or well-optimized fonts, with font-display: swap, and few variants.
• Less JavaScript: every third-party script (chats, pixels, maps) has a cost. Remove the ones you don't use.
• Good hosting with a content delivery network (CDN) and Brotli or gzip compression.

Structured data: helping Google understand you

schema.org JSON-LD markup explains to Google what your site is: your organization, your articles, your location, your frequently asked questions. It's not a ranking trick, but it reduces ambiguity and can enable rich results. Validate it with Google's Rich Results Test.

How to measure your progress

1. Run PageSpeed Insights on your home page and on two inner pages, on mobile.
2. Write down your real LCP, INP and CLS (if your site has enough traffic) and the lab score.
3. Verify the site in Search Console and review indexing and performance.
4. Fix one thing at a time and measure again in two weeks.