How to write useful alt text for content images丨What should be written in IMG ALT

How to Write Effective IMG ALT Text:

1. Precise Description (80-125 characters, avoid redundant words like “image”)
2. Naturally Include Keywords (1-2 keywords can increase search ranking by 22%)
3. Differentiate Image Types (Informative images require full description; decorative images use alt=””)

Want your images to rank higher in Google Search? Research shows that optimizing a page’s ALT text boosts click-through rate in image search by 37%, and 430 million visually impaired users globally rely on screen readers to understand image content.

Google’s official guidelines clearly state: Precisely descriptive ALT text significantly improves page relevance score.

E-commerce SEO product images that include Model + Color + Feature (e.g., “iPhone 15 Pro Silver 256GB”) receive 2.3 times more image search traffic than those vaguely written as “smartphone”;

Images using default filenames like “image01.jpg” are directly filtered out by Google Image Search at a rate as high as 81%.

What is Image Alternative Text (ALT Text)

In Google Image Search, over 22% of clicks come from pages with well-optimized ALT text. However, WebAIM’s 2024 study reports that 67% of website homepage images still lack effective ALT descriptions.

ALT Text (Alternative Text) is a core attribute of the <img> tag in HTML, primarily serving three critical functions:

• Accessibility: 430 million visually impaired users worldwide rely on screen readers to read ALT text and understand images;
• SEO Optimization: Google explicitly uses ALT text as a significant factor for image ranking, with precisely described images seeing a 40% increase in search exposure;
• Error Tolerance: When an image fails to load, the ALT text is displayed instead, ensuring information is not lost.

Compliant ALT Text

How to Write Good ALT Text

According to Google’s 2023 Search Quality Report, pages with correctly optimized ALT text have a 42% higher click-through rate in image search results than unoptimized ones.

WebAIM research shows that on e-commerce websites, if product images include ALT text with a complete product description, the user conversion rate can increase by 28%.

However, in reality, about 65% of websites still use ineffective ALT text like “image01.jpg,” directly affecting search engine understanding of image content.

Three Core Principles of ALT Text

(1) Precisely Describe Image Content:

ALT text lengths between 80-125 characters achieve the best indexing results; descriptions exceeding 150 characters have a 23% chance of being truncated. For product images, ALT text containing 3 or more key attributes (e.g., Brand + Model + Color) results in a 41% higher user click-through rate than simple descriptions.

It is essential to avoid redundant phrases like “visible in the image,” which reduce content relevance score by 15%.

• Control length between 80-125 characters; the excess part may be truncated by search engines.
• Content requirements dictate avoiding redundant words like “image” or “photo”; describe the key elements in the image directly.

Example Comparison:

❌ “A picture of a shoe”

✅ “Men’s black leather casual shoe 2024 new model”

(2) Naturally Include Keywords:

Search Engine Land’s comparative experiment showed that naturally integrating 1-2 keywords into ALT text can increase image search impressions by 22%, but exceeding 3 keywords leads to an 18% drop in ranking.

Best practice is to integrate keywords into a complete sentence, such as “Professional photographer taking a landscape photo with a Sony A7IV camera.”

Choose variants of the page’s main keyword and avoid stuffing (e.g., “shoes running shoes men’s shoes Nike discount”).

In terms of optimization effect, ALT text containing 1-2 keywords sees an average 22% increase in image search ranking, but over-optimized ALT text may cause a 15% drop in ranking.

(3) Differentiate Image Types:

• Informative images need a full description of the content (e.g., charts, diagrams)
• Functional images should describe the function (e.g., “Search button,” “Shopping cart icon”)
• Decorative images use empty ALT (alt="")

ALT Text Writing for Different Scenarios

(1) E-commerce Product Images:

Shopify platform statistics show that ALT text containing specific material descriptions (e.g., “top grain cowhide”) increases product conversion rate by 19%.

Multi-angle display images adopt a three-part structure: “Product Name + Perspective + Detail” (e.g., “iPhone15 Pro rear camera close-up”), which can increase image search traffic by 53%.

Adding year information to seasonal products (e.g., “2024 Autumn/Winter New Model”) brings an additional 31% click-through rate.

Essential elements include Product Name, Key Attributes (Color, Size, Material), and Key Selling Points.

Examples:

• “iPhone 15 Pro Max 256GB Deep Space Black with Anti-shake Camera”
• “Children’s pure cotton short-sleeve T-shirt Summer new model Blue size 120”

When displaying multiple angles, the ALT text for each image should be different:

• “Product front view display”
• “Product side view close-up”
• “Product detail craftsmanship”

(2) Blog Images:

Ahrefs research indicates that tutorial screenshots using the format “Software Name + Step + Number” (e.g., “Photoshop color adjustment step 3”) increase user task completion rate by 38%.

If the ALT text for a data chart summarizes the core conclusion (e.g., “Market Share: Company A 45%”), the content sharing rate increases by 27%.

Labeling a person’s complete identity (e.g., “Professor Li from Tsinghua University speaking”) increases the professional score by 42%.

• “WordPress backend theme installation step 3” (Tutorial type)
• “2024 Global Smartphone Market Share Pie Chart” (Data chart)
• “Expert giving a speech at a technology summit” (Person photo)

(3) News Images Must Include Five Elements:

AP’s image usage guidelines show that news images with ALT text containing the five elements (Time + Location + Person + Event + Action) are 58% more likely to be cited by other media.

For major events, including the specific date in the ALT text (e.g., “September 15, 2024”) can increase search impressions by 37%.

Example:

• “2024 Paris Olympics opening ceremony fireworks display”

ALT Text Writing for Different Images (with Practical Cases)

Google Image Search accounts for 22.6% of all web searches, and images with well-optimized ALT text receive 53% more clicks than unoptimized images.

Shopify data shows that images on e-commerce product pages with complete product descriptions in the ALT text have a 31% higher conversion rate than those simply labeled “product image.”

WebAIM’s 2024 survey found that 58% of websites still use ineffective ALT text like “IMG_001.jpg.”

• E-commerce Product Images: ALT text containing product name and key attributes extends user dwell time by 40%;
• Infographics: ALT text summarizing core data increases share rate by 28%;
• Person Photos: ALT text stating the person + setting increases citation times by 35%.

ALT Text Writing for E-commerce Product Images

(1) Basic Product Display Images

Amazon 2024 sales data shows that ALT text containing 3 or more product attributes (Brand + Model + Key Parameter) increases conversion rate by 31%. Among them, electronic products must specifically note technical specifications, such as “iPhone 15 Pro Max 6.7-inch A17 chip.” This complete description results in a 47% higher click-through rate than simple descriptions.

Clothing products should include material information; product images labeled “pure cotton” have a 23% higher conversion rate than those not labeled.

Essential Elements:

• Full product name
• Key attributes (color, size, material)
• Important features

Examples:

• “Apple Watch Series 9 45mm Starlight with Cellular Functionality”
• “Children’s non-slip rain boots Yellow size 26 Rubber material”

(2) Multi-Angle Display Images

eBay platform research indicates that multi-angle ALT text using the structure “Product Name + Perspective + Detail” can increase the product page dwell time by 42 seconds.

Best practice is to provide a unique perspective description for each image, such as “Backpack front view display / Internal storage compartment close-up / Waterproof zipper detail.” This structured writing is adopted by 78% of professional photography teams.

Tests show that detail image ALT text containing the keyword “close-up” increases the likelihood of a user zooming in to view by 35%.

Perspective Labeling:

• “Product front view display”
• “Product side view close-up”
• “LOGO detail close-up”

Complete Case Study:

Different angles of a backpack:

• “Black double-shoulder backpack Front overall display”
• “Black double-shoulder backpack Internal compartment detail”
• “Black double-shoulder backpack Shoulder strap adjustment buckle close-up”

(3) Usage Scenario Images

Wayfair home decor case studies show that scenario image ALT text including the usage environment (e.g., “Grey fabric sofa placed in a modern style living room”) has a 58% higher click-through rate than simple product descriptions.

Clothing scenario images that state “Model height 175cm wearing size M” can reduce the return/exchange rate by 37%.

It is recommended to use the three-part structure: “Product + Scenario + Effect,” such as “Chef using a professional-grade food processor to prepare ingredients.” This writing style is adopted by 65% of food bloggers.

Description Method: Product + usage scenario + person (optional)

Examples:

• “Woman walking on campus wearing a black double-shoulder backpack”
• “Coffee machine usage scene on a kitchen countertop”

ALT Text Writing for Informative Images

(1) Data Charts

The Economist survey found that ALT text using the format “Chart Type + Core Conclusion” (e.g., “Bar chart: Q3 revenue growth 25%”) increased data comprehension efficiency by 42%.

Financial charts must include units of measurement; charts labeled “Unit: Ten thousand USD” reduce user misinterpretation rate by 53%.

Avoid vague phrases like “as shown in the figure,” which reduce professional scoring by 28%.

Key Writing Points:

• Explain chart type
• Summarize core conclusion
• Avoid detailed data

Example Comparison:

❌ “Sales data chart”

✅ “2024 Q2 smartphone market share: Apple 35%, Samsung 28%”

(2) Flowcharts / Diagrams

MIT research shows that flowchart ALT text using the structure “Process Name + Key Step Count” (e.g., “User registration flowchart: 5 steps”) increases operation success rate by 31%.

Diagrams in technical documents should include component names, such as “Engine working principle diagram: Components 1-5 labeled.” This writing style is adopted by 72% of engineering manuals.

Note that steps should be connected by arrows, not numbered lists.

Description Method:

• Explain chart purpose
• Key steps overview

Case Study:

“Website construction flowchart: Requirement analysis → Prototype design → Front-end development → Testing and launch”

(3) Infographics

Social Media Examiner statistics show that infographics whose ALT text summarizes the core point (e.g., “Global social media user distribution: Asia accounts for 42%”) have a 33% higher share rate than detailed descriptions.

Health-related infographics must include the data source; those noting “WHO 2024 data” see a 45% increase in credibility score.

It is recommended to keep it within 100 characters, focusing on the 1-2 most critical data points.

Optimization Strategy:

• Summarize core point in ALT
• Supplement detailed explanation in the body text

Example:

“Global carbon emission source distribution: Energy production 42%, Transportation 28%”

ALT Text Writing for Person and Scene Photos

(1) News Person Photos

AP guidelines require person photo ALT to include “Name + Title + Scene.” Media images that adhere to this are 52% more likely to be cited. Academic conference photos should note “Professor Li from XX University speaking at the 2024 AI Summit.” This writing style increases the professional score by 47%.

Avoid vague terms like “expert group photo,” which reduce search visibility by 63%.

Five Elements: Person’s name + identity + location + time + action

Example: “Professor Zhang Wei delivering a keynote speech at the 2024 Artificial Intelligence Conference”

(2) Team Photos

LinkedIn data shows that ALT text labeling the number and identity of team members (e.g., “XX Tech 2024 core team 10 people group photo”) increases corporate homepage visits by 35%.

It is recommended to use the structure “Occasion + Team + Number,” such as “Annual sales champion team 8 people receiving an award.” This writing style is adopted by 68% of HR departments.

Note: Do not list all personnel names; keep it concise.

Description Method: Scene + person’s identity + number of people

Case Study:

“XX Company 2024 Annual Outstanding Employee Commendation 10-person team photo”

(3) Location Photos

TripAdvisor analysis points out that travel photo ALT text containing seasonal features (e.g., “Winter Jiuzhaigou Snow Scene”) has a 58% higher click-through rate than ordinary descriptions.

Architectural photos should specify the design style, such as “Gothic church spire close-up.” This professional description increases collection volume by 42%.

It is recommended to use the structure “Location + Feature + Time,” avoiding subjective descriptions like “beautiful scenery.”

Key Information:

• Location name
• Notable features
• Time (optional)

Example:

“Shanghai Bund night view Oriental Pearl Tower lit up”

ALT Text Writing for Functional Images

(1) Navigation Icons

W3C accessibility tests show that functional icon ALT text using the structure “Action + Element” (e.g., “Search button”) achieves a 98% recognition accuracy with screen readers.

It is recommended to uniformly use “View Shopping Cart” for the shopping cart icon instead of “Shopping Basket.” This standardized phrasing increases conversion rate by 15%.

Avoid vague instructions like “click here,” which increase operational confusion by 42%.

Description Principle: Function + element type

Examples:

• “Shopping cart icon”
• “Return to top button”

(2) Social Media Icons

Hootsuite research shows that social icon ALT text using the format “Platform + Function” (e.g., “Twitter share button”) can increase click-through rate by 23%.

It is recommended to use official platform names uniformly, such as “LinkedIn” instead of “领英.” This consistency increases brand recognition by 37%.

Note that icons for different platforms should have separate ALT text; do not use a unified “social icon.”

Naming Convention: Platform name + icon

Case Study:

“Facebook homepage link icon”

(3) Button Images

Baymard Institute found that action button ALT text containing action verbs (e.g., “Buy Now”) has a 29% higher conversion rate than static descriptions (e.g., “Red button”).

Key buttons are recommended to use the first person, such as “My Orders” having a 17% higher click-through rate than “User Orders.”

Avoid redundant phrases like “click to submit”; keep it concise and powerful.

Key Writing Points: Action description + button

Examples:

• “Buy Now button”
• “Membership registration button”

Practical Tool Recommendations

1. ALT Text Check: Google Lighthouse
2. Batch Modification Tool: Adobe Photoshop’s “Export for Web” ALT text option
3. CMS Plugin: WordPress‘s “Auto Image Alt” plugin

Common Error Correction Table

5 Common ALT Writing Errors

Google’s 2024 Search Quality Report shows that about 68% of websites have improper use of ALT text, resulting in an average loss of 37% in image search traffic.

WebAIM research points out that product images with incorrect ALT text on e-commerce websites have a 29% lower conversion rate than optimized ones.

Images using default filenames (e.g., IMG_001.jpg) are filtered out by Google Image Search at a rate as high as 83%.

Here are the five most common ALT text errors:

1. Keyword Stuffing: Causes a 15-20% drop in search ranking
2. Too Brief Description: User bounce rate increases by 42%
3. Ignoring Functional Images: Violates WCAG 2.1 accessibility standards
4. Using the Same ALT Text: Judged as low-quality content
5. Relying on AI auto-generation for ALT: Accuracy is less than 35%

Error One: Keyword Stuffing

(1) Specific Manifestation

Google Search Console data shows that ALT text with keyword stuffing accounts for about 23% of problematic images, mainly characterized by repeating the same keyword more than 3 times (e.g., “phone smartphone 5G phone”).

Amazon platform audit found that such non-compliant ALT text has a 47% probability of causing product images to be filtered.

Typical features include: using more than 5 keywords, repeating brand names (e.g., “Nike Nike shoes NIKE”), and including irrelevant promotional words (“discount special offer free shipping”).

• Stuffing multiple irrelevant keywords into the ALT text
• Repeating the same keyword multiple times

Example:

❌ “Running shoes Nike shoes men’s shoes 2024 new discount cheap”

(2) Negative Impact

SEMrush experiments show that ALT text with keyword stuffing causes an average drop of 18 positions in image search ranking. Screen reader tests show that such ALT text leads to an error rate of up to 62% in comprehension, requiring users an extra 15 seconds to distinguish effective information.

Google’s algorithm will flag this behavior as “over-optimization,” reducing the EEAT score of the entire page by 23%.

• Google may judge this as a spamming behavior
• Image search ranking drops by 15-20%
• Poor user experience for screen reader users

(3) Correction Method

Ahrefs recommends using the structure “Brand + Core Attribute + Differentiating Selling Point,” such as “Adidas Ultraboost running shoes black energy return midsole.”

Tests show that this natural inclusion of 1-2 keywords can boost search impressions by 35% while maintaining 98% accessibility compliance.

The key is to ensure every modifier has practical meaning and avoid filling in useless words.

• Choose 1-2 core keywords
• Naturally integrate them into the product description

Corrected Example:

✅ “Nike Air Force 1 sports shoe 2024 spring new model”

Error Two: Too Brief Description

(1) Common Cases

WebAIM survey points out that 42% of websites have ALT text that is too brief, with invalid descriptions like “image” and “icon” being the most common (37%). In e-commerce, 23% of product images only state the category name (e.g., “dress”), preventing Google from identifying the specific product.

On news websites, 19% of accompanying images use vague phrases starting with “Pictured is…”.

• Only write “image,” “photo,” or “chart”
• Product images only state the category name

Examples:

❌ “Phone”

❌ “Meeting photo”

(2) Data Impact

Images with brief ALT text have a 58% probability of being skipped by users during mobile first-screen loading. 73% of screen reader users encountering such images choose to leave the page directly.

This type of ALT text causes a 41% loss in image search traffic, missing out on many long-tail keyword opportunities.

• User bounce rate increases by 42%
• Image search click-through rate decreases by 55%
• Visually impaired users cannot get effective information

(3) Optimization Plan

Moz recommends using the “5W1H” principle to expand the description: What (item), Who (person), Where (setting), When (time), Why (purpose), How (feature).

For example, optimizing “Phone” to “Photographer using an iPhone 15 Pro to capture the Northern Lights landscape.”

• Supplement with key attribute information
• Reach a length of 80-125 characters

Optimized Example:

✅ “iPhone 15 Pro Max 256GB Deep Space Black with Dynamic Island design”

Error Three: Ignoring Functional Images

(1) Typical Scenarios

WAVE detection report shows that 85% of websites have missing ALT text for functional images, with search icons (62%), shopping carts (58%), and social sharing (49%) being the top three.

• Navigation menu icons have no ALT
• Form submission buttons have no description
• Social media icons are not labeled

Example:

❌ Search icon using alt=””

(2) Correct Writing

W3C recommends using a verb structure of “Action + Object,” such as “Expand Menu button” or “Submit Order button.” For social icons, it should state “Go to [Platform],” such as “Go to Twitter page icon.”

• Describe the function of the button/icon

Corrected Examples:

✅ “Site search button”

✅ “Facebook homepage link icon”

Error Four: Using the Same ALT Text for All Images

(1) Common Situation

38% of e-commerce websites have the problem of multiple images sharing the same ALT text, with clothing products (different colors/styles) being the highest proportion (47%).

On content websites, 28% of accompanying images use bulk-copied ALT text.

This lazy practice leads Google to judge 75% of images with repeated ALT as “low-value content.”

• Multi-angle product images use the same ALT
• Article images use bulk-copied ALT

Example:

❌ Three different angle watch images all use “Watch display”

(2) SEO Impact

Google Image Search categorizes images with identical ALT text as duplicate content, causing a 40% drop in impressions. Tests show that writing differentiated ALT text for multi-angle product images (e.g., “Front/Side/Detail”) can increase image search traffic by 89%.

This practice can cover more long-tail keywords, bringing 27% long-tail keyword rankings to the page.

• Judged as low-quality content by Google
• Image search impressions decrease by 40%
• Misses out on long-tail keyword opportunities

(3) Solution

It is recommended to establish an ALT template system: use “Brand + Model + Parameter” for the main product image, add a “close-up” suffix for detail images (e.g., “Lens coating close-up”), and specify the usage environment for scene images (e.g., “Outdoor hiking scene”).

Amazon big seller data shows that systematic writing achieves 98% ALT uniqueness.

• Write unique ALT text for each image
• Differentiate based on shooting angle and focus

Correct Example:

1. “Watch front view worn on wrist”
2. “Watch dial scale detail close-up”
3. “Watch strap buckle structure display”

Error Five: Relying on Auto-Generated ALT

(1) Main Issues

MIT research shows that CMS auto-generated ALT text has an accuracy of only 31%. Common errors include: misidentifying the subject (28%), missing key information (39%), and using generic words (33%).

In the default ALT of the WordPress media library, 47% are invalid names like “image123.”

• CMS auto-generated ALT text has low accuracy
• Frequently uses invalid words like “image” or “photo”

Example:

❌ “image_20240815_01”

(2) Quality Data

Comparative tests show that manually optimized ALT text has a 63% higher search click-through rate and 42 seconds longer user dwell time than auto-generated versions.

Incorrect automatic ALT can cause misinformation, such as identifying a “diabetes meter” as a “thermometer.” The error rate in the medical field is as high as 15%, posing significant risks.

• Auto-generated ALT has a 63% lower search click-through rate
• User dwell time is shortened by 28 seconds
• Cannot accurately describe complex images

(3) Improvement Measures

It is recommended to adopt an “AI pre-screening + manual verification” model: first use tools like Adobe Sensei to generate a draft, then have an editor add professional details.

The New York Times practice shows that this semi-automated process can increase ALT production efficiency by 3 times while maintaining 92% accuracy.

• Manually review image ALT text
• Set up rules for automatic ALT generation
• Use AI assistance tools (requires manual verification)

Optimization Effect Comparison Table

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