Website speed test

Many visitors arrive on a phone, and Google ranks by the mobile version of a page. Enter a web address to run Google's Lighthouse test on a simulated mid-range phone and see which parts of the page slow it down.

What it checks

What this tool checks

Speed

Server response. Time to the first byte, measured from our server.
Compression. Gzip or Brotli on the HTML.
Mobile speed score. Google Lighthouse on a simulated mid-range phone.
Core Web Vitals. Largest Contentful Paint, layout shift and main-thread blocking.

Security and HTTPSalso checked

HTTPS and redirect. The site loads securely, and http:// addresses forward to https://.
Certificate. Trusted, matching the domain, and how many days until it expires.
TLS version. TLS 1.2 or 1.3; older versions are refused by current browsers.
Security headers. HSTS, content type, framing, referrer and content security policies.

Email authenticationalso checked

MX records. Which servers receive mail for the domain.
SPF. One record that lists the servers allowed to send as you.
DKIM. A signing key under the 20 most common selector names.
DMARC. A policy telling receivers what to do with mail that fails the checks.

Search basicsalso checked

Title and description. Present, and a length that fits in search results.
Headings and language. One H1, and the page language declared.
Mobile viewport. Phones get the mobile layout, which Google uses for ranking.
Canonical and indexing. No accidental noindex, and one preferred address per page.
robots.txt and sitemap. Crawlers are let in and can find every page.
Sharing preview. Open Graph title and image for links shared on social apps.

The three numbers that matter

Largest Contentful Paint is how long the main content takes to appear; under 2.5 seconds is good. Layout shift measures how much the page jumps around while loading; under 0.1 is good. Blocking time is how long scripts keep the page from responding to taps; under 200 milliseconds is good.

When Google has enough data from real Chrome users of the site, the result also shows how fast the page loads for them. That real-world figure is what Google uses for ranking.

Why the score moves between runs

Lab tests vary with server load, ads, third-party scripts and network conditions on the day. Differences of a few points between runs are normal. Look at the metrics and the fix plan rather than chasing a single number.

FAQ

Frequently asked questions

Why test on mobile?

Google indexes and ranks the mobile version of every page, and phones have slower processors and connections than desktops. A page that is fast on a phone is fast everywhere.

What is a good score?

Google rates 90 to 100 as good, 50 to 89 as needing improvement and below 50 as poor. Chat widgets, sliders and tracking scripts are the usual reasons a business site scores low.

Why is my server response slow?

Usually because every page is built from scratch on each visit. Page caching, a CDN, or fixing slow database queries and plugins brings it down. The fix plan lists the steps.

Free tools