Did you know that the images on your online store could be the single biggest thing slowing it down — and hurting your Google rankings at the same time?
Most small business owners upload product images straight from their camera or design software without a second thought. But those uncompressed, unoptimised images can be ten, twenty or even fifty times larger than they need to be — adding seconds to your loading time, frustrating customers and pushing your store down in Google search results before anyone even sees your products.
The good news is that image optimisation is one of the quickest wins available in SEO. Most of the fixes take minutes and require no technical skills whatsoever. This guide walks you through everything you need to know.
Why Images Affect Both Speed and SEO
Images affect your store in two distinct but connected ways. First, oversized images slow your pages down — and as we covered in Post 26, a slow page loses more than half its visitors before it even finishes loading. Second, images with no descriptive information give Google nothing to work with — and Google cannot see images the way humans can. It reads the file name and the alt text to understand what an image shows. Without that information, every image on your store is essentially invisible to search engines.
Optimising your images fixes both problems simultaneously — faster loading and better SEO from the exact same set of actions.
5 Steps to Optimising Every Image on Your Store
Step 1 — Compress every image before uploading. The most impactful single thing you can do for your store's speed is to compress your images before uploading them. Compression reduces the file size of an image without meaningfully reducing its visual quality. A product image that starts at 5MB can typically be compressed to under 200KB with no visible difference to the customer. Use free tools like TinyPNG, Squoosh or Shopify's built-in image compression to reduce your file sizes before every upload. For your existing product images, go through your store systematically and replace any oversized images with compressed versions.
Step 2 — Use the correct image dimensions. Uploading a 4000x4000 pixel image for a product thumbnail that displays at 600x600 pixels is like driving to the corner shop in a lorry — you are using far more than you need. Resize your images to the actual dimensions they will be displayed at before uploading. For Shopify product images, 2048x2048 pixels is the recommended maximum for zoom functionality. For blog post featured images, 1200x630 pixels is ideal. Matching your image dimensions to their display size significantly reduces file size and loading time.
Step 3 — Choose the right file format Not all image formats are equal in terms of file size and quality. JPG is best for photographs and complex images — it compresses well and displays beautifully. PNG is best for images with transparent backgrounds or simple graphics where you need crisp edges. WebP is a newer format that offers the best of both — smaller file sizes than JPG or PNG with excellent quality. Shopify automatically converts uploaded images to WebP format for browsers that support it, but you can also convert images to WebP yourself before uploading for even better results.
Step 4 — Write descriptive, keyword-rich alt text for every image Alt text is the written description of an image that search engines read to understand what the image shows. It is also read aloud by screen readers for visually impaired users — so it serves both an SEO and an accessibility purpose. Every product image, blog post image and collection banner on your store should have a descriptive alt text that includes your primary keyword naturally. Instead of leaving the alt text blank or using a generic file name like "IMG_4521.jpg," write something like "printable business budget planner template for small business owners PDF." This tells Google exactly what the image shows and who it is for.
Step 5 — Rename your image files before uploading The file name of your image is another signal Google uses to understand what it shows. A file named "DALL_E_2024_12_28_product_image.webp" tells Google nothing. A file named "business-budget-planner-template-small-business-owners.webp" tells Google exactly what the image is. Before uploading any image to your store, rename the file using descriptive, keyword-rich, hyphen-separated words. This takes thirty seconds per image and contributes meaningfully to your overall image SEO over time.
Build Your Image SEO Into Your Overall SEO Strategy
Image optimisation is one component of a complete SEO strategy — and it works best when it is part of a systematic, ongoing approach to improving your store's visibility and performance.
👉 SEO Strategy Worksheet → A structured worksheet to help you audit every aspect of your store's SEO — including your images — and build a clear, prioritised action plan so you are always working on the fixes that will have the biggest impact on your rankings and your traffic.
Start with your top ten product images this week. Compress them, rename them, resize them and add keyword-rich alt text. Then work through the rest of your store systematically. The cumulative effect on your speed and rankings will be significant — and every new image you upload from this point forward will already be optimised from the start.
