Image SEO Checklist for E-Commerce

Product images are one of the most underused SEO assets in e-commerce. Most shops put enormous effort into photography — lighting, staging, multiple angles — and then upload the images with filenames like IMG_4821.jpg and no alt text. That's leaving a significant amount of organic traffic on the table.

This checklist covers everything you need to get your product images properly optimised for search.

File Names

Rename your files before uploading. Search engines read filenames as a relevance signal.

Use hyphens (not underscores) to separate words. Keep it descriptive but concise — product name, colour, material, category.

Alt Text

Alt text is the single most important image SEO field. Every product image needs one, including secondary and zoom images.

• Describe what's in the image specifically — colour, material, context
• Include the product name and a relevant keyword naturally
• Keep it under 120 characters
• Don't start with "Image of" or "Photo of" — Google ignores the prefix

Image Dimensions and Format

Google considers page speed as a ranking factor, and oversized images are one of the most common causes of slow load times.

• Use WebP as your primary format — typically 30–50% smaller than JPEG at the same quality
• Serve images at the size they're displayed — don't load a 3000px image into a 600px slot
• Use srcset to serve different sizes to different screen widths
• Aim for under 100 KB per product image

Structured Data (Schema.org)

Adding Product schema to your product pages enables rich results in Google — including image carousels, price, and availability directly in search results.

{
  "@context": "https://schema.org",
  "@type": "Product",
  "name": "Red Leather Chelsea Boots",
  "image": "https://yourshop.com/images/red-leather-chelsea-boots.jpg",
  "description": "Handcrafted red leather chelsea boots with stacked heel.",
  "offers": {
    "@type": "Offer",
    "price": "129.00",
    "priceCurrency": "EUR",
    "availability": "https://schema.org/InStock"
  }
}

Image Sitemaps

A standard XML sitemap lists your pages — but an image sitemap tells Google specifically about the images on those pages, including their title and caption. This increases the chance of your images appearing in Google Images.

<url>
  <loc>https://yourshop.com/products/red-leather-chelsea-boots</loc>
  <image:image>
    <image:loc>https://yourshop.com/images/red-leather-chelsea-boots.jpg</image:loc>
    <image:title>Red Leather Chelsea Boots</image:title>
    <image:caption>Handcrafted red leather chelsea boots with stacked heel, available in sizes 36–42</image:caption>
  </image:image>
</url>

Captions

Image captions are read more often than body text — users scan pages and captions catch the eye. They also give search engines additional context about the image.

Not every product image needs a caption, but hero images and lifestyle shots benefit from one. Keep captions factual and concise — under 80 characters.

Lazy Loading

Only load images that are visible in the viewport. For product listing pages with dozens of images, this makes a significant difference to initial load time and Core Web Vitals.

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

Never lazy-load your above-the-fold hero image — it will hurt your Largest Contentful Paint (LCP) score.

The Metadata Bottleneck

The biggest obstacle to implementing this checklist at scale is metadata. Writing accurate alt text, titles, and captions for hundreds or thousands of product images manually is time-consuming and inconsistent.