Image SEO: Alt Text, File Names & Compression (2026)

Images are an easy SEO win most sites ignore. Here's how to optimize alt text, file names, and image size for rankings, accessibility, and speed.

Images make up most of a typical page's weight, yet image SEO is one of the most-skipped quick wins. Done right, it helps accessibility, page speed, and Google Images traffic.

Alt text

Alt text describes an image for screen readers and search engines. Write a short, accurate description of what's in the image, include a keyword only if it fits naturally, and skip "image of" — it's redundant. Decorative images can use empty alt="".

File names

Rename IMG_4821.jpg to something descriptive like blue-running-shoes.jpg before uploading. Google reads file names as a relevance signal for image search.

Compression & format

• Serve WebP/AVIF where you can — far smaller than JPEG/PNG.
• Resize to the dimensions you actually display (don't ship a 4000px image into a 400px slot).
• Lazy-load below-the-fold images so they don't block first paint.

Check your pages

The free Audit SEO tool flags missing alt text and oversized images in seconds. For a full-site image and speed audit, Semrush or SE Ranking crawl every page automatically.

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