--- name: responsive-images description: "Use when reviewing article images, cards, galleries, or any component rendered at multiple sizes across breakpoints. Check both the markup and the CSS layout because an incorrect `sizes` attribute can negate a perfectly good `srcset`." metadata: category: images priority: high difficulty: intermediate estimatedTime: "20" source: frontendchecklist.io url: https://frontendchecklist.io/en/rules/images/responsive-images --- # Implement responsive images with srcset Serving a 2000px image to a 400px phone screen wastes bandwidth and slows loading—srcset lets the browser download only the size it needs. ## Quick Reference - Use srcset to provide multiple image sizes - Use sizes attribute to tell browser which size to download - Browser selects optimal size based on viewport and DPR - Can save 50-70% bandwidth on mobile devices ## Check Verify that images use srcset and sizes attributes for responsive delivery. ## Fix Implement responsive images with srcset for different screen sizes and resolutions. ## Explain Explain how responsive images deliver optimized versions based on device capabilities. ## Code Review Inspect image markup and component abstractions for `srcset`, `sizes`, and width/height handling. Flag pages that always ship desktop-sized assets to mobile, omit `sizes`, or generate variants that do not match the actual rendered layout. --- For full implementation details, code examples, and framework-specific guidance, see `references/rule.md`. Rule page: https://frontendchecklist.io/en/rules/images/responsive-images