How to Optimise Product Images for Search and Speed

On most online stores, product photos are the single biggest reason the site loads slowly — and slow product pages are one of the fastest ways to lose a sale on mobile. Images now make up roughly half of the average page’s total weight, and on around 85% of desktop pages the largest single element on screen is an image. For a Melbourne retailer with hundreds of product photos, that means image optimisation isn’t a nice-to-have finishing touch. It’s one of the highest-leverage fixes available, and one of the easiest to get wrong. Here’s what it actually involves, and what it should cost to fix properly in 2026.

Why product images are usually the biggest speed problem on your store

A typical desktop page now carries around 2.3MB of data, and images account for close to half of that on their own. Product galleries make this worse than most page types, because a single product page might load a hero photo, four to six thumbnails, and a handful of lifestyle shots, all before a shopper has scrolled past the fold. If those images are uncompressed JPEGs straight out of a camera or supplier feed, that page can easily carry five to ten times more image data than it needs to.

It’s also worth noting that this problem tends to grow quietly. A store that launches with a lean, well-optimised catalogue can end up carrying years of accumulated bloat as new product lines get added by different staff, agencies or supplier feeds, each with their own habits around file size and format. By the time it’s noticeable in day-to-day browsing, it’s usually already affecting Core Web Vitals scores and, by extension, how Google evaluates the page experience of your store.

The real cost of slow, unoptimised product images

The numbers here are hard to ignore. Every extra second of load time costs an estimated 7% in conversions, and 53% of mobile shoppers abandon a page that takes more than a few seconds to load. Brands that fully implement responsive images — serving the right image size for each device rather than one large file to everyone — see an average 24% improvement in mobile conversion rate and a 31% reduction in mobile bounce rate compared with stores serving the same oversized image to every visitor. For an online store already spending on traffic, that gap sits entirely on the table: the shoppers already arrived, they just left before the page finished loading.

Format	Typical size vs. JPEG	Browser support in 2026
JPEG	Baseline	Universal
WebP	~25–35% smaller	~97–98% of browsers
AVIF	~50% smaller	~93% of browsers

Google’s own web.dev guide to WebP images is a useful practical reference here — it’s the same guidance Chrome’s own performance auditing tool, Lighthouse, checks your site against.

What “optimising” a product image actually means

Optimisation isn’t just running images through a compressor once and moving on. A proper approach covers:

• Format — serving WebP or AVIF to browsers that support them, with a JPEG fallback for the few that don’t.
• Correct dimensions — generating multiple sizes (a “srcset”) so a phone downloads a phone-sized image, not a desktop-sized one shrunk down in the browser.
• Compression level — finding the quality setting where file size drops significantly with no visible loss for a shopper deciding whether to buy.
• Lazy loading — only loading images as a shopper scrolls to them, rather than every image on the page loading immediately.
• Descriptive alt text and filenames — which affects accessibility and image search visibility as much as it affects speed.

Alt text and filenames: the SEO half of the equation

Image optimisation isn’t only about speed — it’s also a genuine traffic source in its own right. Google Images drives a meaningful share of all web search traffic, and product pages where the alt text and filename directly match the product name and key attributes see roughly 47% higher image impression rates than generic filenames like “IMG_4021.jpg”. Stores that optimise this consistently across their catalogue report around 40% higher traffic from Google Images specifically. Google’s own Image SEO best practices documentation covers this in detail — the short version is that alt text should describe what’s actually in the photo (for example, “navy blue merino wool jumper, front view” rather than just “jumper” or the product SKU).

A practical workflow for optimising product images

For a Melbourne store working through an existing catalogue, this is usually the most efficient order of operations:

1. Keep a high-resolution master file for every product, stored separately from what actually gets uploaded to the site.
2. Batch-export web versions in WebP (and AVIF where your platform supports it), with a JPEG fallback generated automatically.
3. Generate at least three sizes per image for responsive serving — mobile, tablet and desktop — rather than one fixed size for everyone.
4. Set lazy loading for every image below the first screen of content.
5. Write specific, descriptive alt text for each product image as part of the product listing process, not as an afterthought.
6. Submit an image sitemap so Google can discover and index your product photos directly.

What this costs and how long it takes for a Melbourne store

For a small catalogue (under 100 products), a one-off image optimisation pass is typically a few days of work, often bundled into a broader technical SEO fix. For a larger store running into the thousands of product images, expect a proper project rather than a quick task — batch processing tools handle the bulk conversion, but responsive sizing, alt text and sitemap work still need a human check to avoid generic, unhelpful descriptions being applied automatically across the board. The upside is that unlike a lot of SEO work, the return here is measurable almost immediately: page speed scores and Core Web Vitals results improve as soon as the images go live, well before any ranking changes show up.

Ongoing maintenance matters just as much as the initial clean-up. New product photos are usually the ones that slip back into old habits first, particularly when they come from a supplier feed or a photographer who isn’t briefed on your site’s format and sizing standards. Building a short checklist into your product upload process — format, size, alt text — is a small process change that prevents most of the problem from creeping back in over the following twelve months.

How this fits into your wider e-commerce SEO

Image optimisation is one piece of a broader technical picture for online stores. We covered several other quick wins — duplicate URLs, title tags, product schema, category pages and broken links — in our Shopify SEO checklist for Melbourne online retailers, which is worth working through alongside this if you haven’t already. Our e-commerce SEO service covers image optimisation as a standard part of an ongoing technical health check for growing stores.

Frequently asked questions

Will optimising my images actually improve my Google rankings, or just my page speed?
Both, though through different mechanisms. Faster pages improve the Core Web Vitals signals Google uses as part of page experience, while descriptive alt text and filenames make your product photos discoverable through Google Images search directly — a separate traffic source most Melbourne stores barely tap into.

Do I need to manually optimise every single product photo?
No. Format conversion, compression and responsive sizing can all be automated through your platform or a plugin. The one part that genuinely benefits from a human — writing specific, accurate alt text — is worth doing properly rather than automating with generic templates, since generic alt text captures very little of the search benefit.

What’s a realistic file size target for a product photo?
As a rough guide, aim for well under 200KB per product image after optimisation, even for a large, detailed hero shot — modern compression and formats like WebP and AVIF make this achievable without a visible drop in quality on a typical product page.

Can I just install a compression plugin and call it done?
A compression plugin handles part of the job well — usually format conversion and basic compression — but it won’t fix generic alt text, missing responsive sizes, or a missing image sitemap on its own. Treat a plugin as one step in the workflow above rather than a complete solution, and check its output on a handful of product pages after installing it to confirm image quality still looks right at typical zoom levels.