Tool · A test runs in under a minute per URL

PageSpeed Insights

Google · Google (web.dev) Free Beginner

This is the standard free tool for measuring how your page actually performs, and it defaults to a mobile view, which is exactly what you want when most of your visitors are on a phone. It runs your page on a throttled connection and gives you real Core Web Vitals plus a prioritized list of what is slowing you down. Start here: measure before you change anything, so you know whether your fixes actually helped.

• Run the mobile test first and read the Largest Contentful Paint number, that is your real load feel on a phone.
• The Opportunities and Diagnostics sections tell you exactly what to fix, usually oversized images and render-blocking scripts.
• Field data (real Chrome users) beats the lab score when it is available, so trust that number more.