Image SEO is often overlooked, but optimized images can drive significant traffic through Google Image Search and improve your overall page rankings. Here's everything you need to know.

Why Image SEO Matters

Google Image Search drives billions of searches monthly
Core Web Vitals heavily depend on image optimization
Rich results often feature images prominently
User engagement increases with quality images

The Complete Image SEO Checklist

1. Use Descriptive File Names

Before uploading, rename your files with descriptive, keyword-rich names:

Bad: IMG_2847.jpg

Good: blue-nike-running-shoes.jpg

Tips for file names:

Use lowercase letters
Separate words with hyphens (not underscores)
Include relevant keywords naturally
Keep it concise but descriptive

2. Write Effective Alt Text

Alt text helps search engines understand your images and improves accessibility:

Bad: alt="image"

Better: alt="shoes"

Best: alt="Blue Nike Air Max running shoes on white background"

Alt text guidelines:

Describe the image accurately
Include your target keyword if natural
Keep it under 125 characters
Don't start with "Image of..." or "Picture of..."
Be specific and contextual

3. Optimize File Size

Page speed is a ranking factor. Compress your images to improve load times:

Use WebP format (25-35% smaller than JPEG)
Compress to 70-80% quality
Aim for under 100 KB for most web images
Use fatpng to compress without quality loss

4. Choose the Right Dimensions

Don't rely on CSS to resize images. Upload them at the correct display size:

Match the actual display dimensions
Use responsive images with srcset
Avoid scaling up small images

5. Implement Responsive Images

Use the HTML picture element or srcset attribute to serve different image sizes for different screen widths. This ensures mobile users download smaller images while desktop users get high-resolution versions.

Key attributes to use:

srcset: Define multiple image sources with their widths (e.g., 400w, 800w, 1200w)
sizes: Tell the browser which image to load based on viewport width
width/height: Always include dimensions to prevent layout shift

6. Add Width and Height Attributes

Always include width and height attributes on your img tags to prevent Cumulative Layout Shift (CLS). For example, if your image is 800 pixels wide and 600 pixels tall, include width="800" and height="600" in the tag.

7. Use Lazy Loading

Add loading="lazy" to images below the fold. This defers loading until the user scrolls near them, improving initial page load time. Don't lazy load above-the-fold images (like hero images) - they should load immediately.

8. Create an Image Sitemap

Help Google discover your images by including them in your sitemap. Add image:image elements within your URL entries, specifying the image location and title. This helps search engines index your images more effectively.

9. Use Structured Data

Add schema markup for products, articles, and recipes to enable rich results in search. Include an "image" property in your JSON-LD structured data to associate images with your content. This can help your images appear in Google's rich results and image carousels.

10. Consider Image CDN

Use a CDN to serve images faster globally:

Cloudflare
Cloudinary
imgix

Technical SEO for Images

Format Selection

Use Case	Recommended Format
Photographs	WebP (JPEG fallback)
Graphics/logos	SVG or PNG
Animations	WebP or MP4
Icons	SVG

Core Web Vitals Impact

LCP (Largest Contentful Paint): Often your hero image - optimize it heavily
CLS (Cumulative Layout Shift): Always specify dimensions
FID (First Input Delay): Large images can block the main thread

Common Image SEO Mistakes

Missing alt text - Every image needs descriptive alt text
Generic file names - "image1.jpg" tells Google nothing
Oversized images - Don't upload 5000px images for 500px displays
Keyword stuffing - Don't cram keywords into alt text unnaturally
Missing dimensions - Causes layout shifts that hurt rankings
Blocking with robots.txt - Don't block /images/ from crawling

Measuring Success

Track your image SEO performance:

Google Search Console - Check the Performance report with "Search Type: Image"
PageSpeed Insights - Monitor Core Web Vitals
Google Analytics - Track traffic from image search

Conclusion

Image SEO is a combination of technical optimization and good content practices. Compress your images, write descriptive alt text, use proper file names, and implement responsive images. These steps will improve both your search rankings and user experience.

How to Optimize Images for SEO