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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/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.

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For full implementation details, code examples, and framework-specific guidance, see references/rule.md.

Rule page: https://frontendchecklist.io/rules/images/responsive-images