How to Write Alt Text for Images to Improve Accessibility and SEO Guide

Let’s be honest for a second. Most people treat alt text like an administrative chore. They toss a random keyword into the image description backend of WordPress, hit publish, and pray to the search engine gods. I’ve audited hundreds of sites over the past decade. Do you know what I usually find in the alt attribute fields? Garbage like “IMG_4929.jpg” or keyword-stuffed abominations like “best running shoes cheap deals sale online.” It hurts to look at. Not only does this alienate millions of screen-reader users, but it also leaves massive organic traffic on the table. Trust me on this: search engines are way smarter than they were ten years ago, and your sketchy keyword stuffing isn’t fooling anyone. Let’s fix that right now.

The Dual Purpose of Alt Text: Accessibility Meets Search Engine Optimization

Here is the core misunderstanding holding back your web pages: you think alt text is just for Google. It’s not. Alternative text was born out of pure necessity for people who cannot see your visuals. When a screen reader hits an image tag, it reads that description aloud. If your text says “banner,” the user gets zero context. If it says “A close-up of a barista pouring oat milk into a ceramic mug, creating a heart-shaped latte art design,” the user gets the exact experience you intended.

Now, let’s talk about the search engine side of the equation. Google’s crawlers are blind. They rely on surrounding text, page context, and yes—the alt attribute—to understand what an image depicts. According to the Google Search Central guidelines, descriptive alt text helps crawlers index your visual assets correctly, which directly feeds traffic into Google Images. More importantly, it signals topical relevance to the broader algorithm. If your page is about a specific technical process and your images accurately describe step-by-step actions, your semantic authority goes through the roof. It is a win-win.

How to Write Alt Text That Doesn’t Suck: The Golden Rules

I’ve noticed a lot of contradictory advice floating around SEO blogs. Some gurus tell you to write a paragraph. Others say keep it to one word. Both are wrong. Here is the framework I use every single day.

• Be concise, not cryptic. Aim for 125 characters or less. Screen readers often cut off after that threshold, and frankly, humans lose focus too.
• Context is king. An image of a black screen means something totally different on a photography portfolio versus an electrical engineering blog. Describe what matters for *this specific page*.
• Never start with “Image of” or “Picture of.” Screen readers already announce that it’s an image. Don’t waste precious characters stating the obvious.
• Use keywords naturally—or not at all. If your main keyword fits the description organically, drop it in. If it sounds forced, scrap it. Google can read the room.

Handling Complex Visuals, Infographics, and Decorative Images

Not all images are created equal. Some require a nuanced touch. Let’s break down the tricky categories so you don’t get caught guessing.

Infographics and Data Visualizations

If you upload a massive data chart, a 10-word alt tag won’t cut it. The alt text should state the core takeaway, while the detailed breakdown belongs in the surrounding body text or a dedicated longdesc attribute. As the W3C Web Accessibility Initiative points out, complex images need a clear path to the underlying data so no user is left in the dark.

Decorative Images

Sometimes an image is just there to look pretty. A wavy divider line, a background texture, or a generic abstract blob. What do you do with these? You leave the alt attribute empty (alt=””). Do not delete the alt attribute entirely—that causes validation errors in some screen readers. Just leave the quotes blank. This tells assistive tech to gracefully skip the asset entirely.

Product Photos

E-commerce sites are notoriously bad at this. “Blue shirt” tells the user nothing. Instead, use: “Men’s slim-fit organic cotton crewneck t-shirt in heather navy.” Include color, material, and style if it matters to the buyer. You are writing for conversion as much as accessibility.

Common Alt Text Mistakes That Will Tank Your Rankings

I see the same mistakes over and over again. Let’s clear them out of your workflow once and for all.

Keyword Stuffing: “Alt text for SEO search engine optimization best ranking tricks strategies 2024.” Stop it. This looks like spam to users and triggers algorithmic penalties from search engines. Write for humans first.

Redundancy: If the caption directly underneath the photo already says “CEO Jane Doe speaking at the annual conference,” your alt text shouldn’t repeat that exact phrase word-for-word. Screen readers will read both, creating an annoying, repetitive loop for the user.

Vague Descriptions: “Photo” or “Graphic” or “Placeholder.” These are completely useless. If you can’t be bothered to describe the asset, you shouldn’t be publishing it.

Frequently Asked Questions

Should every single image on my website have alt text?

No. Functional or purely decorative images should have empty alt attributes (alt=””) so screen readers ignore them. Only images that convey meaning or value need descriptive alt text.

How long should my alt text be?

Keep it under 125 characters whenever possible. If an image requires a massive explanation, like a complex flowchart or a financial graph, summarize the main point in the alt text and provide the full breakdown in the surrounding text.

Can I use the exact same alt text for identical images used across different pages?

It depends on the context. If the image serves the exact same purpose and means the same thing in both locations, yes. However, if the context changes, adapt the alt text to match the specific page’s narrative.

Does Google penalize missing alt text?

Google doesn’t explicitly penalize you with a ranking drop just for missing alt text, but you are leaving massive traffic on the table. You miss out on Google Images traffic and fail basic web accessibility standards, which can indirectly impact user engagement metrics.