Image SEO: Complete Guide to Optimizing Images

Why Image SEO is a Goldmine

Google Images is the second largest search engine in the world. For e-commerce sites, recipe blogs, or travel guides, image search can drive 20-30% of total traffic. Moreover, optimized images are crucial for Core Web Vitals (specifically LCP) and overall user experience.

5 Steps to Perfect Image SEO

1. File Names: The First Signal

Before you even upload an image, look at the filename. Google's crawlers look at this to understand what the image is about.

• Bad: IMG_8293.jpg or Screen Shot 2025-01-01.png
• Good: mens-leather-jacket-black.jpg

Tip: Use hyphens (-) to separate words, not underscores.

2. Alt Text: Accessibility Meets SEO

Alt text (alternative text) serves two purposes: it helps visually impaired users understand the image (via screen readers), and it tells Google what the image depicts.

• Context: Detailed description of the image content.
• Keywords: Include main keyword if relevant, but don't stuff.

Example:

<!-- Bad -->
<img src="pancakes.jpg" alt="pancakes">

<!-- Spammy -->
<img src="pancakes.jpg" alt="best pancakes fluffiest pancakes breakfast recipe food porn">

<!-- Good -->
<img src="pancakes.jpg" alt="Stack of fluffy blueberry pancakes topped with maple syrup">

3. Choose the Right Format (WebP, AVIF)

Stop using heavy PNGs for photos.

• JPEG: Good for photos, decent compression.
• PNG: Use only for images needing transparency or simple graphics/logos.
• WebP / AVIF: Recommended. These modern formats offer 30-50% better compression than JPEG without losing quality.

4. Compression (Don't Upload 5MB Files!)

A common mistake is uploading raw images from a camera. A 5MB image can take seconds to load on mobile/3G.

• Target Size: Aim for under 100KB for large banner images, and under 30KB for smaller graphics.
• Tools: TinyPNG, Squoosh.app, or ImageOptim.

5. Lazy Loading

Lazy loading stops the browser from loading images until the user scrolls near them. This dramatically speeds up the "initial load" of your page.

Native Lazy Loading:

<img src="image.jpg" loading="lazy" alt="...">

Note: Do NOT lazy load your main hero image (LCP element), as it can hurt performance metrics.

Image Sitemaps

If your content effectively relies on images (like a gallery or product page), consider adding images to your XML sitemap to help Google discover them.

Structured Data for Images

For recipes, products, or videos, adding Schema Markup can help your images appear as "Rich Results" (e.g., a recipe card with a thumbnail in search results).

Is your Alt Text missing? Use our Free SEO Checker to scan your page. It highlights every image missing an alt tag so you can fix accessibility and SEO issues instantly.