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Why Alt Text Matters for Accessibility & SEO

Image Alt Text Best Practices for SEO

By
James Gibbons
Image Alt Text for Website Accessibility & SEO

In today's digital age, images play a pivotal role in conveying information & enhancing user experience on the web. Amidst this visual appeal, the significance of making these images accessible to all is often overlooked. Not everyone has the privilege of seamless internet connectivity or the ability to perceive visual content.

This is where the often underestimated alt text comes into play. Alt text serves as a textual description of images. It enables those with visual impairments or technical limitations to comprehend & engage with the content.

This blog will delve into the intricate relationship between alt text, accessibility, and SEO. Explore how this often neglected element can significantly impact user experience & website visibility.

What is Alt Text?

Alt text, or alternative text, is an HTML attribute that provides a text description for images for users who use screen readers or search engine crawlers.

Alt text is essentially a brief description you attach to a website image that makes content more accessible to visually impaired people.

It also becomes visible to all users when the image fails to load, thereby preserving the flow and context of your content. These alt text can be added to the HTML code of your website. The format is as follows:

Image Alt Text HTML Code
Image Alt Text HTML Code

For those using content management systems (CMS) like WordPress, Webflow, etc., there's a dedicated field for alt text whenever you upload an image.

Aside from improving web accessibility, alt text boosts your website's SEO. Web crawlers used by search engines to index your site can't "see" images, but they can read alt text. Helping search engines better understand & index your content enhances your website’s visibility in SERP.

Alt Text Examples

Example 1: An image showing a group of students sitting in a classroom, listening to a lecture.

Alt text: Students engaged in a lecture in a classroom setting.

Why this example is good:

1. The alt text is concise and descriptive, providing a clear understanding of what is depicted in the image.

2. It uses keywords that are relevant to the content of the image, such as "students," "lecture," and "classroom."

3. It avoids using generic phrases like "image of" or "photo of."

Example 2: An image showing a person using a wheelchair to access an accessible ramp.

Alt text: A person in a wheelchair using an accessible ramp to enter a building.

Why this example is good:

1. The alt text is specific and accurate, describing the exact action being performed in the image.

2. It uses inclusive language, avoiding ableist stereotypes or assumptions.

3. It highlights the accessibility features of the environment.

Optimal Alt Text Format

The optimal format for image alt text includes the following elements:

1. Description: The alt text should be a clear, concise, and accurate description of the image. It should aim to accurately represent the content and function of the image within the context of the specific page.

2. Use of Keywords: For SEO, it's crucial to use relevant keywords in your alt text. However, avoid keyword stuffing because it might be penalized by search engines. Keywords should be added naturally within the context of the image.

3. Unique: Each image alt text should be unique to the specific image. Do not copy and paste the same alt text into multiple images.

4. Avoid Filler Words: Avoid using unnecessary words like "Image of" or "Picture of" in the alt text. Screen readers inform users that they're reading an image, so this becomes redundant.

5. Appropriate to the Image: If your image is a functional image used to trigger some activity (like a submit button), then the alt text should describe the function, not the image content.

Remember, the purpose of alt text is two-fold: to make web content accessible for visually impaired users and to help search engines better understand the content of your images.

Image Alt Text vs Image Caption

People often keep their image alt text & image caption or title text the same, but these two attributes serve different purposes. Let us understand the difference between both of them:

Aspect Image Alt Text Image Caption
Purpose Describes the content of the image to aid accessibility and SEO. Provides additional information or context about the image and are visible to all users.
Accessibility Essential for screen readers to describe images to visually impaired users. Though they can be read by screen readers, they are more for the comprehension of sighted users.
Character Limit It should be concise and descriptive, usually within 125 characters. There is typically no set character limit for image captions. However, they should be concise and directly related to the image.
Best Practice Focus on describing the content and context of the image accurately. Captions should provide context or supplemental information. They should be concise and should not repeat the same information provided in the content or alt text.
SEO Provides context to search engines about what the image is about, aiding in image and web search rankings. Though not as important for SEO as alt text, captions can contain keywords and improve the overall on-page SEO.

Importance of Image Alt Text for Accessibility & SEO

1. Enhances Accessibility: Alt text aids visually impaired users who rely on screen readers by providing a textual description of what’s in an image. This way, even if the image fails to load or the user cannot see the image, they can still understand the content through the alt text.

2. Boosts SEO Ranking: Search engines cannot see images but can read text. Using relevant alt text allows search engines to understand your image better, helping your page rank higher in image search results.

3. Acts as a Ranking Factor: The proper use of alt text can contribute to the page’s contextual relevance, a ranking factor for search engines. Correctly optimized alt text with strategic keywords can positively influence SERP rankings.

4. Improves User Experience: Alt text helps clarify the image context & relevance to the surrounding content. It can also be beneficial when images cannot be viewed due to technical issues or slow internet speed. It offers users an understanding of what should be there.

How to Write Alt Text: Best Practices

The alt text should be very crisp & informative. It should describe the image within 125 characters & give a clear idea of what the image is about.

Using relevant keywords judiciously rather than stuffing your alt text with them is essential, which search engines can see as spam. Let us learn the best practice in detail:

Use Accurate and Relevant Alt Text Descriptions

Start by identifying the most critical elements of the image. Say you have an image of a sunflower field at sunset. A simple yet effective alt text could be "Sunflower field at sunset".

These accurate & relevant descriptions in your alt text can help users & search engine crawlers understand the context of the image.

Avoid stuffing your alt text with keywords, as search engines see this as spammy behavior.

Remember that alt text's primary purpose is accessibility, not keyword optimization. However, if your keywords naturally fit into the image's description, then by all means, include them. It helps search engines understand the relevancy of the image to the overall content, boosting your image's visibility in image search results.

Be Specific with Image Alt Text

Being specific in your alt text is essential. The more specific you are, the easier it is for users & search engines to understand the image's exact context. It helps bots determine how valuable an image is for a user.


For example, if your image features a woman wearing a blue polka dot dress, instead of writing "woman in a dress" as the alt text, a more specific one would be "woman in blue polka dot dress".

Keeping your alt text specific & concise can increase your chances of ranking higher for relevant search queries.

Keep Alt Text Short & Simple

Most screen readers cut off alt text at around 125 characters, so keeping your descriptions around this length is best.

When writing, focus on the most critical details of the image. Does the color of the dress matter? Or is it more important to focus on the action the woman in the image is doing?

Write in plain, understandable language. While it's tempting to use technical terms or industry jargon, remember that your alt text should be understandable to as wide an audience as possible.

Keeping your alt text short & simple ensures visitors & search engines can quickly grasp the content of your image. It improves the user experience & potentially boosts your image’s visibility & organic traffic.

Avoid Using Filler Words in Alt Text

Starting your alt text with phrases like "Image of" or "Picture of" is unnecessary, as search engines & screen readers already assume this information. The focus should be on providing useful alt text that describes the nature or content of the image.

Eliminating unnecessary phrases makes your descriptions easier for search engines to understand.

For example, instead of "Image of a golden retriever playing fetch", write "Golden retriever playing fetch". The latter is concise & straight to the point, effectively communicating the image's content.

Make sure your alt text communicates the intended message without including unnecessary phrases. Remember, good alt text should stand on its own and convey the same purpose as the image, even if the image does not load or can't be seen by users.

Make Alt Text Keyword-Rich

Having a relevant keyword inside your alt text helps search engines understand what the image is about. It helps improve your page’s relevancy to users' search queries.

Remember, keyword stuffing is frowned upon by search engines.

Always ensure that your chosen keyword naturally fits into the description of your image. For instance, if you're selling summer dresses and have an image of one, your alt text could be "yellow summer dress with flower patterns".

This approach can boost your page’s ranking on search engines for the keyword you used in your alt text. Also, it may increase the chances of your images appearing in relevant image search results, thereby driving more organic traffic to your website.

Identify & Add Missing Alt Text With Quattr

In conclusion, image alt text is indispensable in both accessibility & SEO. It enhances the usability of websites for visually impaired users & individuals with image-loading issues.

Incorporating relevant, concise, and informative alt text helps search engines understand the context & relevancy of images, leading to improved visibility and ranking.

However, manually checking your CMS for missing alt texts can be cumbersome, time-consuming, and error-prone. This is where Quattr becomes your valuable assistant.

The Quattr SEO platform effortlessly analyzes your web pages and shows your score against each image alt text. The score ranges from 1 to 100, with the 100 being most optimized. You can check the score against each image & can add and optimize your image alt text.

While Quattr can help optimize SEO & accessibility for your website, you can optimize your alt text right now. Use our free AI image alt text generator to get keyword-rich, relevant alt images. This tool allows you to generate SEO-friendly image alt-text suggestions within seconds.

With Quattr, not only can you ensure your website adheres to accessibility guidelines, but you can also optimize your content & improve your SEO ranking.

Analyze & Generate SEO-Friendly Image Alt Texts With Quattr

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Alt Text FAQs

Does every image require alt text?

Not every image requires alt text. Decorative images, complex charts, and images already described nearby may not need alt text. However, it's crucial to consider the context and purpose of each image to determine whether alt text is necessary.

How does alt text affect image loading times?

Alt text doesn't affect image loading times directly; its primary function is improving web accessibility & SEO ranking. The load time is more correlated with image file size& server speed. When images fail to load, alt text provides textual context that can be indexed by search engines, upholding user experience.

How often should alt text be updated for SEO purposes?

Alt text should be updated whenever your website's visual content changes significantly. It includes changes such as adding a new image or a change in the purpose of the image.

About The Author

James Gibbons

James Gibbons is the Senior Customer Success Manager at Quattr. He has 10 years of experience in SEO and has worked with multiple agencies, brands, and B2B companies. He has helped clients scale organic and paid search presence to find hidden growth opportunities. James writes about all aspects of SEO: on-page, off-page, and technical SEO.

About Quattr

Quattr is an innovative and fast-growing venture-backed company based in Palo Alto, California USA. We are a Delaware corporation that has raised over $7M in venture capital. Quattr's AI-first platform evaluates like search engines to find opportunities across content, experience, and discoverability. A team of growth concierge analyze your data and recommends the top improvements to make for faster organic traffic growth. Growth-driven brands trust Quattr and are seeing sustained traffic growth.

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