Image SEO — How Alt Text, File Names, and Compression Affect Rankings

Why Image SEO Matters

Google Images drives significant traffic. Properly optimized images also improve your page's overall SEO through faster loading (Core Web Vitals) and better accessibility.

Alt Text Best Practices

Alt text describes the image for screen readers and search engines.

Good Alt Text

• "Golden retriever playing fetch in a park" (descriptive, specific)
• "Screenshot of the image compression tool interface" (contextual)
• "Bar chart showing website loading times before and after optimization" (informative)

Bad Alt Text

• "image1.jpg" (filename, not description)
• "photo" (too vague)
• "best cheap online free image compressor tool 2026 compress images" (keyword stuffing)

Rules

• Be descriptive but concise (125 characters or fewer)
• Include relevant keywords naturally
• Do not start with "image of" or "picture of"
• Use empty alt="" for decorative images

File Naming

Name files descriptively before uploading:

• Good: golden-retriever-park.jpg
• Bad: IMG_20260415_143022.jpg, screenshot.png, untitled.jpeg

Use hyphens to separate words (not underscores or spaces).

File Size Impact on Rankings

Google explicitly considers page speed as a ranking factor. Images are usually the heaviest page elements.

Targets:

• Hero images: Under 200 KB
• Blog images: Under 100 KB
• Thumbnails: Under 30 KB

Image Sitemap

Include important images in your sitemap for better indexing:

<url>
  <loc>https://example.com/page</loc>
  <image:image>
    <image:loc>https://example.com/image.jpg</image:loc>
    <image:caption>Description of the image</image:caption>
  </image:image>
</url>