Image optimization might not be the flashiest SEO tactic, but in the world of e-commerce, it’s one of the most underestimated performance levers. With product-heavy pages, mobile-first indexing, and increasing user expectations around site speed, how you manage your images directly affects both rankings and revenue.
While adding alt text alone won’t send your pages flying up the SERPs, small improvements — when scaled across hundreds or thousands of product images — can compound quickly.
In this article, we break down five core components of effective image optimization for online retailers, including the latest best practices and platform nuances (yes, we’re looking at you, Shopify).
1. Format selection isn’t trivial: Why WebP is now the default
Choosing the right image format is foundational. It’s a balance between compression, quality, and browser compatibility.
Use case breakdown:
- JPEG: Ideal for product photos, lifestyle shots, and complex images.
- PNG: Best for images that require transparency (logos, icons).
- WebP: Modern format with superior compression and visual quality — supported by most major browsers and used by default on platforms like Shopify.
According to Google’s Web Vitals documentation, switching to next-gen formats like WebP or AVIF can reduce image file size by up to 34%, directly improving LCP (Largest Contentful Paint) scores. If your platform doesn’t convert images to WebP automatically, tools like Squoosh can help automate this at scale.
2. Image filenames aren’t just internal housekeeping
Uploading images as IMG_0938.jpg or final-final-banner2.png is a missed opportunity. Search engines parse filenames as a weak ranking signal, and descriptive names also aid internal asset management.
Best practice:
- Use hyphens (not underscores) to separate words
- Include product name + view/type (e.g., travel-pillow-bat-front.jpg)
This is especially useful when you repurpose images across category pages, promotional banners, or social media ads, and want to maintain consistency and findability.
3. Alt text: Still important, but not for the reasons you think
Alt text remains critical, not as a quick-win Image SEO tactic, but for accessibility and contextual relevance.
A few rules of thumb:
- Be descriptive, not keyword-stuffed
- Mention what’s actually in the image
- Keep it brief, yet specific
Example:
- Red cricket bat standing upright on a wooden rack
- Buy cheap cricket bats online best prices fast shipping
Bonus tip: Generative AI tools like ChatGPT or Gemini can assist in bulk alt text creation. Just validate outputs for tone and accuracy before pushing them live.
4. Resize and compress for performance — every time
Many retailers upload ultra-high-resolution images (4000×4000 pixels) without realizing they’re being rendered in a 500×500 space. This leads to bloated file sizes, poor mobile performance, and slower load times.
Recommendations:
- Set max image dimensions appropriate to their layout location
- Use responsive images (srcset) where possible
- Compress all images before upload (use lossy or lossless methods depending on format)
Research from HTTP Archive shows that images still account for over 40% of total page weight on average eCommerce sites.
Compression doesn’t mean compromising on quality, especially when using smart tools that maintain visual fidelity.
5. Lazy loading: Default in Shopify, optional elsewhere
Lazy loading ensures off-screen images only load when a user scrolls near them. This improves initial page load speed and reduces time-to-interactive, especially important for mobile shoppers on slower networks.
Shopify and most modern themes handle this natively via the loading=”lazy” attribute. For custom or headless builds, you may need to implement it manually with JavaScript or lazy-load libraries like Lozad.js.
Google’s PageSpeed Insights tool explicitly flags non-lazy-loaded images as an issue under the “Defer offscreen images” audit.
Final thoughts: Optimization is a multiplier, not a magic bullet
Image optimization isn’t going to fix an eCommerce store’s entire SEO strategy, but it’s a scalable practice that supports site speed, accessibility, UX, and rankings all at once. And when you’re managing hundreds or thousands of SKUs, these micro-improvements add up fast.
If your platform claims to optimize images automatically (like Shopify or BigCommerce), don’t assume it’s done perfectly. Inspect what’s being rendered and test frequently using tools like:
- Google PageSpeed Insights
- Lighthouse in Chrome DevTools
In 2025, Google’s emphasis on Core Web Vitals, accessibility, and mobile-first experiences means eCommerce sites can no longer afford to treat image optimization as an afterthought.