Image Alt Text: Best Practices for SEO

Are you looking for ways to boost your position in the SERPs? Of course you are.

Enter: Image alt text.

Think of it as low-hanging fruit that can be a huge factor in helping you rank higher on search results. Not to mention that it makes your site more accessible to the visually impaired, leveling up your website experience.

So, once you know what image alt tag actually is and why it’s important, you can change the way your site is perceived by both search engines and users.

Let’s dive into the world of image alt text.

What is image alt text?

Image alt text, also known as alternative text, is text that appears alongside an image’s HTML markup, describing what’s in the image. This allows the user to gain some context about the image even when it doesn’t load or is inaccessible in some way. Here’s how alt image HTML may look like:

<img src="example.jpg" alt="Description of the image">

Alt text makes your site more accessible and inclusive as screen readers will read it for visually impaired users. It also makes your site more search-friendly as you can insert relevant keywords in the alt attribute.

Image optimization, including best practices for alt text, is an important aspect of on-page SEO and an essential part of a comprehensive, site-wide technical SEO strategy.

How does image alt text help SEO?

You might not realize it yet, but alt images are a major factor in boosting your SEO performance. Here’s why:

Boosting accessibility

Alt text does more than you think. It’s a lifeline for users with slow internet or those relying on screen readers due to visual impairment. And with about a billion people globally living with visual challenges, this isn’t just about being inclusive (though that’s important!) – it’s about widening your audience and creating a better overall experience for your users.

Helping search engines understand your content

Search engines don’t “see” images the way we do. They rely on alt text to figure out what your image is about and how it fits into the rest of the content on your page. The better your description, the more likely your page will rank well. Basically, if you nail your alt text, you’re making it easier for search engines to do their job – and that means better visibility for you.

Higher SERP rankings

Adding relevant keywords to your alt text is a simple yet powerful trick. It tells search engines, “Hey, this page is super relevant to these queries!” The better the match, the higher you’ll rank. And higher rankings mean your website shows up more often, giving you more visibility in those all-important SERPs.

Improved image search results

Alt text isn’t just for regular search — it’s a golden ticket to image search visibility, too. If you optimize your alt text correctly, your images can pop up in image search results, bringing in visitors who might not have found you otherwise. And with so many people searching through images these days, showing up there can drive a lot of fresh traffic to your site.

Alt tag examples

Crafting good alt text takes a bit of creativity, but it’s absolutely worth the effort. Here are a few examples to show why context, specificity, and relevance are key:

Descriptive product images

Let’s say you’ve got a picture of the new Apple iPhone 16 in pink. A good alt text might be: “Apple iPhone 16 in pink, side view.” It’s concise but gives the essential info — model, color and perspective — making it perfect for ecommerce. On the other hand, something like “Apple iPhone 16 smartphone, pink iPhone, new model” would be overkill. That’s keyword stuffing, which can hurt readability and user experience, so less is definitely more here.

Informative charts and graphs

For a pie chart showing the market share of the top five smartphone brands, a helpful alt text would be: “Pie chart displaying the market share of the top five smartphone brands in 2024.” This beats a generic description like “market share pie chart” because it’s more specific and useful for both screen readers and SEO. Including details like the year and the market context makes all the difference.

Navigational icons

When it comes to icons like a home button, simplicity wins. Alt text like “Home button” is all you need. It might feel too minimal, but there’s no need to complicate it. These images are functional, so keeping the alt text straightforward helps screen readers and web crawlers do their jobs. Adding extra detail here is just overkill. Keep it clean, and you’re good to go!

Logos

When it comes to logos, alt text should be short, descriptive, and aligned with brand integrity. Something simple like “Company X logo” works perfectly. For visually impaired users, this description tells them that the image represents the company, keeping the brand’s identity intact while contributing to an accessible web. It’s all about clarity and recognition—no need for unnecessary flair.

Decorative images

For images that are purely decorative, the best approach is to use alt=””. This tells screen readers to skip over them, preventing unnecessary distractions for users with disabilities. Since these images (like borders or background patterns) aren’t essential for understanding the page content, leaving the alt text empty streamlines the user experience and keeps things focused on what matters.

Image alt text best practices

Alt text plays a key role in making your website both accessible and SEO-friendly, acting as a bridge between how your content is displayed and how it’s understood. Good alt text ensures that visually impaired users can engage with your content while also helping search engines accurately interpret your images.

By following these best practices, you’ll make your site more inclusive and boost your SEO performance:

1. Be descriptive and specific

Good alt text doesn’t just say what’s in the image—it paints a picture. Instead of something vague like “dog,” go for “a dog playing in the park” if it fits your blog’s theme, or even “A Golden Retriever playing fetch in the park” if you’re getting specific. This level of detail helps both visually impaired users and search engines better understand the image, boosting your SEO and increasing the chances of your images showing up in search results, which can lead to more traffic and engagement.

2. Keep it concise

While being descriptive is important, alt text should also be brief. Keep it under 125 characters, focusing on clarity without over-explaining. For instance, “Aerial view of Central Park in New York City” gets the point across without unnecessary fluff. This makes it easier for screen readers to communicate the image’s content without overwhelming users.

3. Include relevant keywords

Alt text is a great opportunity to naturally include your primary and secondary keywords. If you’re writing about Golden Retrievers, you can seamlessly work in those keywords with something like “Golden Retriever playing fetch in the park.”

Just be mindful of keyword stuffing – too many keywords can actually hurt your SEO. If you’re worried about overdoing it, try using variations like “a golden retriever,” “a golden retriever dog,” or “a golden retriever puppy” to keep things natural and varied.

4. Avoid redundant text

Skip phrases like “Image of” or “Picture of” in your alt text — screen readers already alert users that it’s an image. With the goal of keeping alt text concise, it’s best to jump straight into describing the key elements of the image. Cutting out redundant wording helps keep things clean, making it easier for screen readers to provide the important details quickly and efficiently.

5. Focus on functionality

For functional images, like icons or buttons, your alt text should describe their purpose, not their appearance. For example, instead of “Magnifying glass,” use “Search” for a search button. This helps users, especially those relying on screen readers, understand what the button does instantly. Functional images are crucial for navigation, and clear, purposeful alt text improves the overall accessibility of your site.

6. Use empty alt attributes for decorative images

For purely decorative images, use an empty alt attribute (alt=””). This signals screen readers to skip over them, avoiding unnecessary interruptions. While decorative images can enhance your site’s look, they shouldn’t interfere with the browsing experience for users who rely on assistive technology. By using an empty alt attribute, you maintain focus on the essential content, providing a smoother, more accessible experience for everyone.

Alt tag audit

Running an alt tag audit is simple with Similarweb’s Alt Tag Audit tool. Start by navigating to your project, then head over to the ‘SEO’ section, and click on ‘Discoverability’. From there, look for the report titled ‘Links with Images Missing alt Tags’. This report shows you all the images on your site that are missing alt tags or have blank ones.

To address these issues, make sure to add relevant, descriptive alt tags to every image you’re linking to. Not only can this improve your images’ rankings in search listings, but it can also increase visibility for the targeted pages, potentially boosting search traffic and driving more conversions.

Regular site audits are key to staying on top of SEO best practices, ensuring your site is always performing at its best. They also help keep your website accessible and SEO-friendly, so all users can have a seamless experience. By consistently reviewing your alt tags, you not only boost your search rankings but also make sure your site is inclusive and easy to navigate for everyone.

Optimize your alt text for SEO and accessibility

Improving your image alt text is a simple but impactful way to improve both SEO visibility and web accessibility. With Similarweb, you can easily audit and optimize your image alt tags, ensuring you follow industry best practices and achieve real, measurable results.

By reviewing and updating your image alt texts, you make your site is more accessible to all users while also increasing your visibility in search engine results.

Similarweb’s Site Audit quickly identifies missing or incomplete alt tags, allowing you to fix them efficiently. Don’t wait – start optimizing now to improve your rankings and drive more traffic to your website!

With the right SEO tools, your next big growth opportunity is just within reach.

FAQs

Does alt text help SEO?
Yes, alt text helps search engines understand your images, improving your chances of ranking higher in both image search and overall SEO.

How long can alt text be?
Alt text should be no more than 125 characters—short enough for screen readers, but still descriptive.

Should every image have alt text?
Yes, important images need alt text for both accessibility and SEO. For decorative images, use an empty alt attribute (alt=””) so screen readers can skip them.

Can alt text include keywords?
Yes, include keywords naturally in your alt text, but avoid keyword stuffing. Keep it clear and relevant to both users and search engines.

Does alt text affect image load time?
No, alt text doesn’t affect image load time. It’s just a small piece of text used for accessibility and SEO.

by Shai Belinsky

Senior SEO Specialist

Shai, with 8+ years in SEO, holds a Bachelor’s and an MBA. He enjoys TV shows, anime, movies, music, and cooking.