Free Mobile Lighthouse Test
Audit any URL using Google Lighthouse's mobile simulation — 4x CPU throttling, slow 4G network, and 375px viewport. This is the score that influences Google search rankings.
Free Mobile Lighthouse Test
Google uses mobile-first indexing, meaning your mobile Lighthouse score directly impacts your search rankings. Our free tool runs the exact same audit Google uses, simulating a mid-range Android device on a slow 4G connection.
Why Mobile Scores Are Lower Than Desktop
Mobile Lighthouse applies 4x CPU throttling and simulates a slow 4G network (150ms RTT, 1.6 Mbps throughput). The viewport is 375x812 pixels with 3x device pixel ratio. This produces substantially lower Performance scores than desktop — a page scoring 95 on desktop may score 55 on mobile. Google ranks your site based on this mobile score, so closing that gap is often the highest-ROI performance optimization you can make.
What the Mobile Score Measures
The Performance score is a weighted blend of six metrics: First Contentful Paint (10%), Speed Index (10%), Largest Contentful Paint (25%), Total Blocking Time (30%), Cumulative Layout Shift (15%), and Interaction to Next Paint (10%). LCP and TBT are weighted heaviest because they most directly reflect what users experience. A score of 90+ is considered good; below 50 indicates significant performance issues that are likely hurting your rankings and conversion rates.