How to Improve Your Lighthouse Image Score

Lighthouse doesn't give an image-specific score — image audits contribute to the overall Performance score (0–100). Aim for a Performance score of 90+. Clearing all image audit opportunities typically adds 10–30 points to the Performance score, depending on how image-heavy your page is.

Lighthouse analyses technical metrics (file size, format, dimensions), not visual appearance. An image can look perfectly sharp to a human but still fail the audit because it's 2× larger in file size than it needs to be. The audits are about efficiency, not about whether the image looks acceptable.

Lighthouse is the underlying audit engine — it runs in Chrome DevTools and in PageSpeed Insights. PageSpeed Insights runs Lighthouse on Google's infrastructure (simulating a slow mobile connection) and also includes real-world field data from the Chrome User Experience Report (CrUX). They use the same image checks but PageSpeed includes real-user measurements.

Lighthouse scores are weighted — images are important but not the only factor. JavaScript execution time, render-blocking resources, server response time, and Cumulative Layout Shift also contribute. Once images are clean, look at 'Eliminate render-blocking resources' and 'Reduce unused JavaScript' as the next high-impact opportunities.