How to Write Image Alt Text for SEO

If you’re uploading images to your website and skipping the alt text box, you’re leaving both traffic and accessibility on the table.

Let’s fix that.

In this guide, you’ll learn exactly how to write image alt text for SEO — including why it matters, how to do it right, and what mistakes to avoid.

What Is Alt Text For Images?

Alt text (short for “alternative text”) is a short written description you add to an image on your website. Its primary purpose is accessibility — screen readers use it to describe images for visually impaired users.

But alt text also has an important role in SEO.

Search engines like Google (and now AI models like ChatGPT, Claude and Perplexity) read your image alt text to better understand the content and context of your page. When written correctly, it can help your site rank higher in search rankings, get cited in AI overviews and even attract extra traffic from Google Images.

Why SEO Image Alt Text Matters

When optimized properly, your image alt text does the following:

1. Helps Visually Impaired Readers understand your content more clearly. All websites should be designed with accessibility in mind to not alienate potential customers.
2. Gives Google additional Context about your content in a medium other than just written text. When you add visual content to written content, your page is considered potentially more valuable than content written in text only.
3. Improves visibility in image search results (Google Images). If searchers are looking for pictures (think products), this can help your items to be served up first on search engine results.
4. Supports overall on-page SEO by reinforcing keyword relevance. Keywords optimized into alt-text is a fantastic way to get more keyword mentions on the page without having to force it down people’s throats. Because the alt-text box is somewhat hidden, it’s an SEO golden opportunity to use keyword variations when it’s relevant to the photo being used.

Skipping alt text means missing an easy SEO opportunity — especially on product photos, blog graphics, infographics, and service page visuals.

How to Write Image Alt Text for SEO (Best Practices)

First and foremost, think of writing alt text as describing the image to someone who can’t see it. Ideally, if you’ve picked images for your content that directly relate to what you’re talking about, then adding keyword variations into this alt text shouldn’t be too hard.

Follow these three simple rules:

• Be descriptive. Explain what’s actually happening in the image.
• Keep it short. Around 5–10 words is ideal.
• Add SEO keywords naturally. Include your main keyword or a variation only if it fits.

Let’s look at some real examples of SEO image alt text in action.

Example 1: A Perfect SEO Image Alt Text

Here’s a featured image from our post, How Long Does It Take to Learn SEO?

When inspecting the image HTML, the alt text reads:

“A man wonders how long does it take to learn SEO.”

This alt text works well because:

• It accurately describes what’s in the image.
• It includes the keyword “how long does it take to learn SEO” naturally.
• It’s short, clear, and helpful for screen readers.

That’s exactly what good image alt text looks like — descriptive, accessible, and SEO-friendly.

Example 2: Improving Weak Alt Text

Imagine an image of a woman sitting at her computer, gently laughing at what she sees on screen. A generic version of an image alt text might read:

“Woman laughing at computer.”

That’s descriptive but not optimized for SEP.

A stronger, keyword-optimized version of the image alt text could be:

“A woman takes an online course to learn SEO.”

This alt text still describes the image accurately, but it also includes a relevant keyword in a natural way — giving both accessibility and SEO benefits.

Common SEO Image Alt Text Mistakes to Avoid

Even small errors in your SEO image alt text can hurt your site’s accessibility or credibility. When going through your site to optimize image alt text for SEO, avoid these common pitfalls:

• ❌ Keyword stuffing: Don’t jam multiple keyword variations into one description.
• ❌ Misleading text: Never describe an image inaccurately just to fit a keyword.
• ❌ Leaving it blank: Empty alt text = missed opportunity for SEO and accessibility.

As search engines continue to use AI for image recognition, accurate alt text will become even more important. If your description doesn’t match the image, it could lower your content’s quality score.

How to Add Alt Text for SEO in WordPress

If your site runs on WordPress, adding or editing alt text for your images is simple:

1. Open the post or page in your WordPress dashboard.
2. Click the gear icon on the image module.
3. Go to the Advanced tab → find the Image Alternative Text field.
4. Enter your short description (5–10 words) including a natural keyword.
5. Click the green checkmark and save your changes.

That’s it — your SEO image alt text is live.

💡 Pro Tip:
When using stock photos, include the license number in your title text for easy tracking. Keep your alt text focused on accessibility and SEO keywords.

Adding Keyword-Rich Alt Text to New Images

When uploading new media, it’s just as easy to add SEO-optimized alt text to those images as well:

1. Click Add Media in your post.
2. Select or upload your image.
3. Look for the Alt Text field on the right.
4. Write your description using a natural SEO keyword variation.

You can ignore the “Caption” and “Description” fields unless needed — the alt text is the part that matters for SEO.

Quick Checklist for Writing SEO Image Alt Text

Before publishing your next post or page, run through this checklist to make sure you’ve SEO-optimized your alt text for each image:

✅ Describes what’s actually in the image
✅ Includes a keyword naturally (if relevant)
✅ Between 5–10 words long
✅ Unique for each image
✅ Helps both users and search engines

SEO Image Alt Text is a MUST

Alt text for images helps with accessibility first, SEO second — but when done right, it’s a win-win for both.

Write descriptive, concise, keyword-smart alt text for your website’s images, and they will start pulling their weight in your overall SEO strategy.

Next Steps: Strengthen Your Site’s SEO Content!

Want to go beyond images? Check out our complete guide on how to use keywords in content for SEO across your website.

Or, if you’d like the help of the experts, contact us today to get a free website SEO content audit where we’ll go over the existing content assets on your site and give you an SEO action plan for where to go next!