How to Write Alt Text for Images That Helps SEO: Expert Guide

If you’re still treating alt text as an afterthought in your SEO strategy, you’re leaving visibility on the table. Search engines cannot “see” images the way humans do—they rely on textual cues, and alt text is your primary opportunity to tell them what your images actually contain. Beyond ranking benefits, well-crafted alt text makes your content accessible to millions of users who depend on screen readers. This guide covers everything you need to write alt text that satisfies both algorithms and human readers.

What Alt Text Is and Why It Matters for SEO

Alt text (short for alternative text) is an HTML attribute applied to image elements that provides a textual description of an image. When an image fails to load, browsers display this text instead. More importantly, screen readers for visually impaired users read alt text aloud, making it a fundamental accessibility component.

From an SEO perspective, alt text serves as your direct communication channel with search engine crawlers. Google and Bing use alt text as one of many signals to understand image content and context. When you write descriptive alt text, you’re essentially translating your visual content into language that search algorithms can process and index.

Without alt text, search engines still attempt to analyze your images through computer vision and machine learning, but you’re missing a guaranteed, authoritative signal that you control completely. Images with proper alt text can appear in Google Images search results, driving additional organic traffic that many sites completely overlook.

The dual nature of alt text—serving both accessibility and SEO—means it’s one of the few places where what benefits users also benefits your rankings. There’s no trade-off here.

How to Write Alt Text in 5 Steps

Writing effective alt text follows a clear process. These five steps will guide you through creating descriptions that work for both search engines and human readers.

Step 1: Describe the image accurately and specifically. Your primary goal is to convey what the image actually shows. A photo of a golden retriever running on a beach isn’t simply “dog”—it’s “golden retriever running on a sandy beach with ocean waves in the background.” Specificity helps search engines understand exact image content and matches what visually impaired users need to know.

Step 2: Keep it concise while remaining descriptive. Aim for 125 characters or fewer. Google reads longer alt text, but shorter descriptions tend to be more useful. Screen reader users often have to listen to entire alt text descriptions, and unnecessarily wordy descriptions become tedious. “A person typing on a laptop at a coffee shop table” works better than “a professional-looking individual who appears to be working remotely on their laptop computer while sitting at a modern-style coffee shop table with a cup of coffee nearby.”

Step 3: Include relevant keywords naturally. If your page targets “organic coffee beans,” and you have an image of those beans, your alt text should naturally incorporate that phrase. However, the keyword should fit organically within an accurate description—never force it. “Organic coffee beans in burlap sack” reads naturally. “Organic coffee beans keyword rich alt text coffee beans” is obvious keyword stuffing that harms readability without providing SEO benefit.

Step 4: Avoid redundant phrases. Don’t start alt text with “image of” or “picture of.” Screen readers already indicate when they’re reading image content. Saying “image of a sunset” results in “Image of image of a sunset” for users. Simply describe what’s there.

Step 5: Consider context. The same image might need different alt text depending on where it appears. A product photo on a shopping page needs detailed product description. The same photo used decoratively in a blog post might need minimal alt text or none at all if it doesn’t add meaningful content.

Alt Text Examples: Good vs. Bad

Seeing the difference in practice makes this concept clearer. Here are comparisons showing ineffective and effective alt text.

Notice the pattern: good alt text tells someone who cannot see the image exactly what they would see if they could. The shoe example includes brand, model, and distinguishing features. The dashboard screenshot includes specific data points that would be meaningless without the visual.

Best Practices for SEO-Friendly Alt Text

Beyond the core steps, these practices will strengthen your alt text strategy.

Optimize image filenames before writing alt text. Search engines also consider filename context. “IMG_8743.jpg” provides nothing useful. “homemade-chocolate-chip-cookies-recipe.jpg” tells the story before alt text even enters the conversation. Use descriptive filenames with relevant keywords separated by hyphens.

Match alt text to surrounding content. If you’re writing a blog post about email marketing best practices and include a screenshot of an email template, your alt text should describe that specific template in the context of the article. This creates topical coherence that search engines recognize.

Use empty alt text for purely decorative images. Decorative elements that don’t convey content—borders, dividers, stock photos that are purely aesthetic—should have alt text=”” (empty quotes). This tells screen readers to skip them entirely. Many content management systems let you mark images as decorative for this purpose.

Don’t repeat captions as alt text. If you have a visible caption below your image, your alt text shouldn’t duplicate it. Provide additional context instead. The caption might say “Our team in 2024.” The alt text could say “Marketing team of six people posing in office meeting room.”

Test your alt text with screen readers. The only way to truly know if your alt text works is to experience it as a screen reader user. macOS has VoiceOver built in (press Cmd + F5 to activate). Browser extensions like ChromeVox provide similar functionality. Listen to how your content reads.

How to Add Alt Text in Popular CMS Platforms

The technical process of adding alt text varies depending on your content management system.

WordPress: In the block editor, select any image block. The settings panel on the right includes an “Alt Text” field under Image Settings. For classic editor, click an image and select the pencil icon for edit options. WordPress also allows you to set alt text in the Media Library by clicking on individual images.

Shopify: Navigate to Products → All Products, select a product, then click Add Media. Click on any product image, and you’ll see alt text fields in the right panel under “Edit image.” Shopify also allows bulk editing alt text through their product CSV import.

Wix: Click on your image in the editor, then click the Settings icon (gear symbol). Scroll to “Website + SEO Settings” where you’ll find the Alt Text field. Wix also prompts you to add alt text when you first upload images.

Squarespace: Select an image, then click the pencil icon to open the image editor. Scroll down to the “Alt Text” section. Squarespace 7.1 also allows you to edit alt text in bulk through the Media Library.

Common Alt Text Mistakes to Avoid

After reviewing thousands of image implementations, these mistakes appear most frequently.

Keyword stuffing is the most damaging error. Loading alt text with repeated keywords hoping to boost rankings signals manipulation to search engines. Google’s algorithms specifically deprioritize obviously optimized alt text. One naturally placed keyword beats five forced ones.

Vague descriptions provide no value. “Person working” doesn’t tell a blind user anything meaningful. “Accountant reviewing quarterly financial reports at desk” creates a real mental image. The extra detail takes seconds to write and transforms the experience for screen reader users.

Ignoring context entirely. Alt text should relate to the page topic when possible. An image of a clock on a page about time management deserves mention. The same clock image on a page about accounting software is irrelevant and should either be marked decorative or connected to the actual content.

Using the filename as alt text. Automatic alt text generation sometimes defaults to the filename, resulting in something like “DSC_4587_final_edited.jpg.” Always replace these with actual descriptions.

Frequently Asked Questions

Does alt text directly impact Google rankings?
Alt text is a confirmed ranking signal for image search and contributes to relevance scoring for the page overall. However, it’s one of hundreds of factors—don’t expect alt text alone to dramatically change your rankings.

How many characters should alt text be?
Google doesn’t enforce a strict limit, but staying under 125 characters ensures compatibility with all screen readers. Some complex images require more description, and that’s acceptable—just stay concise when possible.

What is the difference between alt text and title text?
Alt text displays when images fail to load and gets read by screen readers. Title text appears as a tooltip when users hover over images in some browsers—it gets minimal SEO value and essentially no accessibility value. Prioritize alt text.

Should I add alt text to every image?
Nearly always, yes. The exception is purely decorative images, which should have empty alt text (alt text=””) rather than no attribute at all.

Final Thoughts

Alt text sits at the intersection of accessibility and SEO—rare territory where doing right by users directly improves your search visibility. The effort required is straightforward: descriptive, concise text that accurately conveys image content.

What holds most people back is treating it as optional rather than essential.

Your images likely represent a significant portion of your content. Without alt text, that content is invisible to search engines and inaccessible to a meaningful segment of your audience. The five-step process works: describe accurately, stay concise, include keywords naturally, avoid redundancy, and consider context.

Start auditing your existing images. If you manage a site with hundreds or thousands of images, prioritize product images, infographics, and content-critical visuals first. The SEO returns compound over time as your image presence in search results grows—and you’re simultaneously making the internet more accessible.