How to Write Effective Image Alt Text for SEO and Accessibility

The primary function of alt text is to describe the contents of an image for those who cannot see it, including individuals who rely on screen reader technology. When an image fails to load due to a poor internet connection, the alt text appears in its place, maintaining the site layout and providing context to the user. From an SEO perspective, search engine crawlers use this text to gain insight into the visual content of a page. This metadata helps these crawlers categorize your images correctly within search results, which can lead to increased traffic through image search queries. In a typical account, neglecting this aspect often results in missed opportunities for organic growth.

Beyond technical performance, alt text represents a commitment to digital inclusivity. Web accessibility standards emphasize that all non-text content must have a text alternative. When you write clear, concise descriptions, you are creating a more usable experience for everyone. Users who navigate via keyboard or screen readers depend on these descriptors to understand the full context of a page. If an image is purely decorative, standard practice involves using an empty alt attribute to ensure screen readers skip over the element, keeping the focus on relevant content.

Writing effective alt text requires balancing descriptive detail with brevity. Aim to describe the image as if you were explaining it to someone over the phone, focusing on the most important elements that convey the meaning of the graphic. Avoid redundant phrases like ‘image of’ or ‘picture of’ because screen readers already identify the element as an image. Instead, focus on the subject matter, the action taking place, or the specific product details that define the visual’s purpose within the article or page layout.

For e-commerce sites, accuracy is even more vital. If you are managing a Shopify store selling professional photography equipment, your alt text should include specific details like camera model names or lens specifications. For example, instead of just saying ‘camera,’ use ‘black mirrorless digital camera with a 50mm lens on a tripod.’ This level of specificity helps search engines match your content with exact user intent. Keep the text under 125 characters to ensure compatibility with most screen reading software, which often truncates longer descriptions during navigation.

Guidelines for writing clear descriptions

• Be specific and concise, focusing on the visual content.
• Include relevant keywords naturally without stuffing them into the text.
• Exclude phrases that add no value, such as ‘image of’ or ‘photo of’.
• Describe the purpose of the image if it is an infographic or a data chart.
• Use empty alt attributes for purely decorative elements to improve focus.

One major mistake is keyword stuffing, which involves packing the alt attribute with irrelevant search terms to manipulate rankings. This practice is counterproductive and flagged by modern search algorithms as spammy behavior. Always write for the human user first. If your alt text does not accurately describe the image, it provides a poor experience for individuals using assistive technology, which conflicts with accessibility best practices. Maintain a natural tone that reflects the actual visual content rather than trying to force high-volume keywords into every single image field.

Another common error is leaving the alt field blank or using generic filenames like ‘IMG_1234.jpg’. These filenames tell both search engines and users nothing about the image. When uploading assets to your content management system, always rename your files to something descriptive before the upload process. Use hyphens to separate words in your filenames, as this helps search engines read the file structure correctly. For example, ‘modern-office-desk-setup.jpg’ is significantly better than a default camera generated filename.

At Alien Road, we integrate accessibility and SEO into our initial site audits and ongoing content management processes. When we take over a project, we first conduct a comprehensive inventory of all images across the domain. We then prioritize high-impact visuals, such as product imagery, service illustrations, and call-to-action buttons. Our team updates the alt attributes to ensure they align with the surrounding text and the overall intent of the page. This systematic approach ensures that every visual asset on the site contributes to the broader marketing goals of our clients.

For example, in a typical engagement for a client launching a new service line, we implement a custom checklist during the final quality assurance phase. This checklist requires developers and content creators to review every image for alt text compliance before the page goes live. We also monitor performance metrics through search console reports to identify if specific images are appearing in relevant image searches. By connecting the technical implementation of alt text to measurable visibility outcomes, we help our clients build more resilient and accessible digital platforms.

Auditing your image library is a continuous task that requires patience and attention to detail. Start by using your content management system’s media library to identify images that lack alt text. Many platforms provide a dedicated column for this metadata, making it easier to spot missing entries. If you have a large number of images, tackle the project in small batches. Focus on your most popular pages first, as these offer the highest potential for organic traffic improvements. Consistent updates over time will yield better results than trying to fix everything in a single day.

You can also use browser-based tools and developer extensions to inspect your site’s alt text in real time. By hovering over images or viewing the site source, you can check whether the alt attribute is present and correctly formatted. If you find errors, document them in a spreadsheet to track your progress. In a typical account, this documentation helps keep the team accountable and ensures that future content uploads follow the same strict standards. Regular audits prevent the accumulation of technical debt and maintain a high level of accessibility across your digital portfolio.