How to Audit Website Images
Learn how to perform an image SEO and performance audit: find unoptimized photos, missing alt text, incorrect dimensions, and legacy formats.
Key Takeaways
- Unoptimized images are the #1 cause of slow Largest Contentful Paint (LCP) scores.
- Audit for missing `alt` attributes to ensure ADA accessibility compliance and image search rankings.
- Exporting an image manifest to CSV with ImgEx simplifies client SEO audits.
Audit any webpage's image footprint
Analyze image sizes, formats, dimensions, and export an audit spreadsheet.
Images usually make up more than 60% of total webpage payload weight. Performing a periodic image audit helps you improve page loading speeds, boost SEO rankings, and maintain accessible web standards.
Key Metrics to Audit
1. **File Size (Weight):** Any single image over 250KB should be compressed or converted to WebP.
2. **Dimensions vs. Display Size:** Serving a 4000px image inside a 300px mobile card wastes immense bandwidth.
3. **Alt Text Accessibility:** Ensure meaningful descriptive text is provided in the `alt` attribute for screen readers.
4. **Format Modernity:** Check whether legacy uncompressed PNGs are being served where WebP or AVIF would save 50%+ file size.
How to Run an Image Audit with ImgEx
1. Scan the target URL in ImgEx.
2. Review the image count, total page image payload, and individual dimensions.
3. Export the full table to CSV to filter by size, format, and missing alt text.
Frequently Asked Questions
What is an ideal target size for web hero images?
Under 150KB–200KB for full-width hero images using modern WebP or optimized progressive JPEG compression.