Come migliorare il punteggio Lighthouse: 4 categorie (2026)

Here's how to improve your Lighthouse score, category by category, starting with the fixes that move the number most.

Google Lighthouse grades a page from 0 to 100 in four categories: Performance, Accessibility, Best Practices and SEO. Each one is scored differently, so the work that lifts one barely touches another. The quickest way to improve a Lighthouse score is to know where the points come from, measure the same way every time, and fix the heaviest-weighted problems first.

This guide covers all four categories. Before you change anything, run your page through a free Lighthouse checker and note the four scores, so you can see what each fix actually does.

How the Lighthouse score works

Every category is scored 0-100, and Lighthouse colours the result: 0-49 is poor (red), 50-89 needs improvement (orange) and 90-100 is good (green).

The Performance score is a weighted blend of five lab metrics. In current versions of Lighthouse the weights are:

That table is the whole strategy for Performance: TBT, LCP and CLS make up 80% of the score. Accessibility, Best Practices and SEO work differently: they're based on pass-or-fail audits, with Accessibility audits weighted by impact on users.

Measure the same way every time

Lighthouse scores vary from run to run, sometimes by several points, because of network conditions, server load, browser extensions and third-party scripts. To see whether a fix helped:

• Use the same tool and the same device profile. Mobile scores are almost always lower than desktop, because mobile tests simulate a mid-range phone on a throttled connection.
• Run it three times and take the middle result for important decisions.
• If you test in Chrome DevTools, use an Incognito window, so extensions don't add their own scripts to the page.

Step 1 — Cut Total Blocking Time (30% of Performance)

TBT is the single biggest Performance weight, and it's mostly about JavaScript. Long tasks on the main thread stop the page from responding while it loads.

• Remove scripts you don't need. Old analytics tags, unused chat widgets and duplicate libraries are common culprits.
• Defer or delay non-critical JavaScript with the defer attribute, or load it after the page is interactive.
• Split large bundles so each page loads only the code it uses.
• Audit third-party scripts. Lighthouse's third-party summary shows which outside scripts block the main thread longest.

Step 2 — Speed up Largest Contentful Paint (25%)

LCP is usually a hero image, a large heading or a video poster. To bring it forward:

• Compress and correctly size the LCP image, and serve a modern format such as WebP or AVIF.
• Don't lazy-load the LCP image. Lazy-loading belongs below the fold; above the fold it delays the main element.
• Preload the LCP resource if the browser discovers it late, for example a background image set in CSS.
• Reduce server response time with caching or a CDN, since nothing can paint before the HTML arrives.
• Remove render-blocking CSS and fonts, or inline the small amount of CSS needed for the first screen.

Step 3 — Stop layout shifts (25%)

CLS measures how much visible content jumps around. The fixes are usually simple:

• Give every image and video width and height attributes, or a CSS aspect ratio, so space is reserved before it loads.
• Reserve space for ads, embeds and banners instead of letting them push content down.
• Load web fonts carefully, for example with font-display and a fallback font of similar size, so text doesn't reflow.
• Avoid inserting content above existing content after the page has loaded, unless the user asked for it.

Step 4 — Fix your Accessibility audits

The Accessibility score comes from automated checks that each pass or fail, weighted by how much they affect people. The common failures are quick to fix:

• Alt text on meaningful images, and empty alt on decorative ones.
• Sufficient colour contrast between text and background.
• Labels on every form field and accessible names on buttons and links.
• A logical heading order and a page language set on the html element.

A perfect Accessibility score doesn't mean a page is fully accessible: automated tests catch only some problems, so test with a keyboard and a screen reader too.

Step 5 — Clear Best Practices warnings

Best Practices looks at security and modern web hygiene. Typical fixes are serving everything over HTTPS, removing errors from the browser console, replacing deprecated APIs, using images with the correct aspect ratio and avoiding third-party cookies where you can.

Step 6 — Pass the Lighthouse SEO checks

The SEO category checks the basics that let search engines crawl and understand a page: a title element, a meta description, a successful HTTP status, crawlable links with descriptive text, a valid robots.txt and correct hreflang and canonical tags. These are often the quickest points of all. Keep in mind that a Lighthouse SEO score of 100 means the basics are in place, not that the page will rank.

How to improve Lighthouse score on WordPress, Shopify and other builders

On hosted platforms and CMSs you can't always change the code, but the same priorities apply:

• Remove apps and plugins you don't use. Each one can add scripts and styles to every page, which raises Total Blocking Time. Deactivating is not always enough; some leave code behind, so check the page source afterwards.
• Pick a lightweight theme. Themes with sliders, animations and several font families on every page are a common cause of slow LCP.
• Use the platform's image tools. Most builders can resize and convert images to WebP automatically if you upload a large enough original.
• Be selective with embeds. Video players, social feeds, chat bubbles and review widgets all load third-party code. Load them only on the pages that need them, or use a lightweight placeholder that loads the full embed on click.
• Use a caching or performance plugin carefully on self-hosted WordPress. Test after enabling each option, because aggressive minification and script delaying can break layouts.

After each change, re-run the Lighthouse checker on the same page and compare the middle of three runs with your starting point.

A quick Lighthouse checklist

• Performance: fewer and lighter scripts, a fast and properly sized LCP image, reserved space for every image and embed
• Accessibility: alt text, contrast, labels, button names, heading order, page language
• Best Practices: HTTPS everywhere, no console errors, no deprecated APIs
• SEO: title, meta description, crawlable links, valid robots.txt, correct canonical and hreflang

Can you get 100 on Lighthouse?

Yes, especially for simple pages on desktop, but it isn't always worth chasing. A 100 on mobile Performance is hard for pages that need analytics, ads or rich media. Aim for green (90+) in every category, then put the remaining effort into content and real-user experience.

Does the Lighthouse score affect Google rankings?

Not directly. Google doesn't use the Lighthouse score itself as a ranking signal. Its page experience signals use Core Web Vitals from real Chrome users, which can differ from a Lighthouse lab run. Improving Lighthouse usually improves real-user speed too, but measure both. Our guide to Lighthouse vs PageSpeed Insights explains the difference.

Why did my Lighthouse score drop when I changed nothing?

Run-to-run variation is the usual answer: network conditions, server load and third-party scripts such as ads change between runs. Re-run the test a few times. If the score stays lower, check whether a plugin, tag or third-party script was added or updated recently.

How often should I check my Lighthouse score?

After every significant change to templates, scripts or hosting, and otherwise monthly. An auto-updating Lighthouse score badge can re-check a page for you on a schedule and show the latest scores.

Related free tools

• Free Lighthouse checker — all four Lighthouse scores for any URL, plus an embeddable badge
• Free page speed test — mobile load time from Google PageSpeed Insights
• Lighthouse vs PageSpeed Insights — why the two scores differ
• Website trust score checker — half its points come from the four Lighthouse scores