Writing Alt Text That Boosts Your SEO Rankings

Alt text used to be an afterthought for accessibility compliance. Today it is one of the most overlooked levers in search engine optimisation. Every product photo on a Sydney fashion boutique's site, every infographic shared by a Melbourne B2B consultancy, and every team portrait on a Brisbane tradie's service page carries a small string of code that search engines use to understand the image. Get it wrong and you leave visibility on the table.

Search engines cannot see images the way humans do. They rely entirely on alt text, file names, and surrounding context to work out what a picture depicts. For Australian businesses competing in saturated local markets, this matters more than ever. When someone searches "best coffee Melbourne CBD," Google Images often decides who gets the click.

This guide walks through how to write alt text that satisfies both accessibility standards and search algorithms, covering what alt text does, how to structure it, common mistakes, and a simple workflow you can apply to every image you publish.

Comparing weak and strong examples is the fastest way to see how alt text shapes image SEO. The scenarios below contrast what many sites publish today with what performs better in search results.

Scenario Weak Alt Text Strong Alt Text
Product photo "shoe" "black leather brogues for men, Australian sizing"
Local landmark "building" "Sydney Opera House at dusk from Mrs Macquarie's Chair"
Team headshot "staff photo" "Dr Sarah Nguyen, dentist at Brisbane Family Dental"
Chart or graph "data" "bar chart showing 34% rise in regional ecommerce sales, 2024"
Decorative divider "line" (leave empty, alt="")

What Alt Text Actually Does for Search Engines

Alt text, short for alternative text, is the descriptive copy attached to an image through the HTML alt attribute. It exists primarily to make the web accessible to screen reader users, but its secondary function is to give crawlers a textual summary of the visual. Google's systems use that summary, alongside the file name and surrounding content, to decide whether an image is relevant to a query.

For local SEO in particular, alt text reinforces geographic signals. A Gold Coast surf shop that uploads a picture of a wetsuit and writes "men's 3mm steamer wetsuit in Burleigh Heads" gives Google far more to work with than a stock-style label such as "IMG_4521" or "image1.jpg". The same principle applies to service businesses across Adelaide, Perth, and regional towns.

The Anatomy of Effective Alt Text

Effective alt text is descriptive, specific, and concise. Most accessibility guidelines suggest keeping it under around 125 characters. The description should communicate what the image shows, not what it looks like in design terms. "Woman holding coffee" is weak; "barista pouring latte art at a Surry Hills café" is informative.

If the image contains text, that text should generally appear in the alt attribute. If the image is purely decorative, such as a background pattern or divider line, the alt attribute should be left empty so screen readers skip it. Treating every image identically is one of the most common slip-ups on Australian e-commerce sites, where category banners and product shots often receive the same generic description.

Common Mistakes That Undermine Image SEO

Stuffing alt text with keywords is still common, and still counterproductive. Google has signalled for years that alt attributes are evaluated for context, not raw keyword density. A picture of a yoga mat described as "yoga mat yoga mats best yoga mat Australia buy yoga mat online cheap yoga" reads poorly to screen reader users and offers no real ranking benefit.

Other frequent errors include uploading images with generic file names like "DSC0002.jpg" and never updating them, leaving alt attributes blank after a CMS migration, and duplicating the same alt text across hundreds of product variations. Australian retailers with large catalogues built through Shopify or WooCommerce often inherit these issues from default theme settings.

How to Research Keywords Before You Write

Good alt text borrows from a wider content and keyword plan rather than inventing descriptions in isolation. Before adding images to a page, it is worth checking what people actually search for in relation to that topic. Google autocomplete, the "People Also Ask" boxes, and dedicated keyword platforms reveal the specific phrases your audience uses.

When you align alt text with the language your customers type into Google, the image pulls double duty: supporting the page's keyword theme while ranking for image-specific queries. Draft page copy first, then return to each image once context is clear. Businesses that invest in keyword research for blog and service pages can extend that discipline to their visuals.

Accessibility and SEO Working Together

Accessibility and SEO are not competing priorities; they reinforce each other. Screen reader users navigating an Australian retail site benefit from clear descriptions just as much as Google's crawlers do, so the same writing principles apply: be specific, describe what matters, and skip what does not.

Under the Disability Discrimination Act, Australian organisations have a legal and ethical obligation to make digital content usable for everyone. Writing alt text with care satisfies that obligation while strengthening organic visibility. Brands producing video content can mirror this discipline across every visual asset, extending transcripts and captions wherever an image sits inside a video or interactive element.

Testing and Refining Your Approach

Audit top landing pages each quarter and confirm meaningful images have descriptions and clean file names. Tools like Screaming Frog, Sitebulb, and Chrome's accessibility checker can surface blank or duplicate alt attributes quickly.

Pay attention to Google Search Console under the Images tab. If pages attract image impressions but few clicks, the alt text may not match what users expect to see. Updating it, along with the file name and caption, can lift click-through rates without touching the rest of the page.

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