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

How to Write Effective IMG ALT Text:

1️⃣ Precise Description (80-125 characters, avoid redundant words like “image”)

2️⃣ Naturally Include Keywords​ (1-2 keywords can boost search rankings by 22%)

3️⃣ Distinguish Image Types (informational images need complete descriptions, decorative images use alt=””)

Want your images to rank higher in Google search? Research shows that webpages optimized with ALT text see a 37% increase in click-through rate in image search, and 430 million visually impaired users globally rely on screen readers to identify image content.

Google’s official guidelines clearly state: ALT text that accurately describes images can significantly improve page relevance scores.

E-commerce SEO product images that include model + color + features (such as “iPhone 15 Pro Silver 256GB”) receive 2.3x higher image search traffic than those with generic descriptions like “smartphone”;

While images using default filenames like “image01.jpg” have an 81% probability of being directly filtered out by Google image search.

 

What is Image Alternative Text (ALT Text)

In Google image search, over 22% of clicks come from webpages with well-optimized ALT text. However, WebAIM’s 2024 research report shows that 67% of homepage images still lack effective ALT descriptions.

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

Accessibility: 430 million visually impaired users globally rely on screen readers to read ALT text to understand images;

SEO Optimization: Google explicitly uses ALT text as an important factor in image ranking, and accurately described images can increase search visibility by 40%;

Fallback Display: When images fail to load, ALT text displays as an alternative, ensuring information is not lost.

Compliant ALT Text

How to Write Good ALT Text

According to Google’s 2023 Search Quality Report, webpages with correctly optimized ALT text have a 42% higher click-through rate in image search results than those without optimization.

WebAIM research shows that e-commerce website product images with ALT text containing complete product descriptions can increase user conversion rate by 28%.

But in reality, approximately 65% of websites are still using ineffective ALT text like “image01.jpg”, directly affecting search engines’ understanding of image content.

Three Core Principles of ALT Text

(1) Accurately Describe Image Content:

ALT text of 80-125 characters in length achieves the best indexing effect, and descriptions over 150 characters have a 23% probability of being truncated. For product images, ALT text containing 3 or more key attributes (such as brand + model + color) has a 41% higher click-through rate than simple descriptions.

Special attention must be paid to avoiding redundant expressions like “visible in the image”, which reduces content relevance score by 15%.

• Length control should be between 80-125 characters, and content beyond may be truncated by search engines.
• Content should avoid using redundant words like “image,” “photo,” directly describing key elements in the image.

Example Comparison:

❌ “A photo of a shoe”

✅”Men’s black leather casual shoes 2024 new model”

(2) Naturally Include Keywords:

Search Engine Land comparative experiments show that naturally incorporating 1-2 keywords in ALT text can increase image search visibility by 22%, but exceeding 3 keywords leads to an 18% ranking decline.

Best practice is to integrate keywords into complete sentences, such as “Professional photographer using Sony A7IV camera to shoot landscapes.”

Choose to use variations of the page’s main keywords and avoid stuffing (such as “shoes sneakers men’s shoes Nike discount”).

In terms of optimization effects, ALT text containing 1-2 keywords improves image search ranking by an average of 22%, but over-optimized ALT text may cause ranking decline by 15%.

(3) Distinguish Image Types:

• Informational images need complete content descriptions (such as charts, diagrams)
• Functional images explain functions (such as “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 (such as “top layer cowhide”) increases product conversion rate by 19%.

Multi-angle display images using the three-segment structure of “product name + angle + detail” (such as “iPhone 15 Pro back camera close-up”) can increase image search traffic by 53%.

Seasonal products with year information (such as “2024 fall/winter new model”) bring 31% additional clicks.

Essential elements include product name, key attributes (color, size, material), and important selling points.

Examples:

• “iPhone 15 Pro Max 256GB Deep Space Black with optical image stabilization camera”
• “Children’s pure cotton short-sleeve T-shirt summer new model blue size 120”

When showing multiple angles, each image’s ALT should be different:

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

(2) Blog Images:

Ahrefs research indicates that tutorial screenshots with ALT text using “software name + step + number” format (such as “Photoshop color grading step 3”) improve user task completion rate by 38%.

If data charts summarize core conclusions in ALT (such as “market share: Company A 45%”), content sharing rate increases by 27%.

Portrait photos with complete identity labels (such as “Professor Li from Tsinghua University speaking”) can increase professionalism rating by 42%.

• “WordPress backend theme installation step 3” (tutorial type)
• “2024 global smartphone market share pie chart” (data chart)
• “Expert speaking at tech summit” (portrait photo)

(3) News Images Should Include Five Elements:

Associated Press image usage guidelines show that news image ALT text containing five elements (time + location + person + event + action) has a 58% higher probability of being cited by other media.

For major events, adding specific dates to ALT (such as “September 15, 2024”) can increase search visibility by 37%.

Example:

• “2024 Paris Olympics opening ceremony fireworks display”

ALT Writing for Different Images (with Practical Examples)

Google image search accounts for 22.6% of total search volume, with ALT-optimized images receiving 53% more clicks than non-optimized images.

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

WebAIM’s 2024 survey found that 58% of websites are still using 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 sharing rate by 28%;
• ​​Portrait Photos​: ALT text describing person + scene increases citation count by 35%.

ALT 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 parameters) increases conversion rate by 31%. Among these, electronic products need to specifically note technical specifications, such as “iPhone 15 Pro Max 6.7 inches A17 chip,” and images with complete descriptions have a 47% higher click-through rate than simple descriptions.

Clothing products should include material information, and 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 connectivity”
• “Children’s anti-slip rain boots yellow size 26 rubber material”

(2) Multi-angle Display Images

eBay platform research shows that multi-angle ALT text using “product name + angle + detail” structure can extend product page dwell time by 42 seconds.

Best practice is to provide unique angle descriptions for each image, such as “backpack front view / internal storage compartment close-up / waterproof zipper detail,” and this structured writing is adopted by professional photography teams at a rate of 78%.

Tests show that detail image ALT containing the keyword “close-up” increases the probability of users zooming to view by 35%.

​​Shooting Angle Labeling​：

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

​​Complete Case Study​：

Different angle images of a backpack:

• “Black backpack front overall view”
• “Black backpack internal compartment detail”
• “Black backpack shoulder strap adjustment buckle close-up”

(3) Usage Scenario Images

Wayfair home furnishings case shows that usage scenario image ALT containing usage environment (such as “gray fabric sofa in modern style living room”) has a 58% higher click-through rate than simple product descriptions.

If clothing scenario images note “model height 175cm wearing size M,” return/exchange rate decreases by 37%.

It is recommended to use the three-segment structure of “product + scene + effect,” such as “chef preparing ingredients with professional-grade food processor,” and this writing is adopted by food bloggers at a rate of 65%.

​​Description Method​: Product + usage scene + person (optional)

​​Examples​：

• “Woman carrying black backpack walking on campus”
• “Coffee machine usage scene on kitchen countertop”

ALT Writing for Informational Images

(1) Data Charts

The Economist research finds that ALT text using “chart type + core conclusion” format (such as “bar chart: Q3 revenue increased 25%”) improves data comprehension efficiency by 42%.

Financial charts need to include measurement units, and charts labeled “unit: ten thousand USD” have a 53% lower user misreading rate.

Avoid using vague expressions like “as shown in the figure,” which reduces professionalism rating by 28%.

​​Writing Key Points​：

• State the chart type
• Summarize core conclusions
• 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 “flow name + key step count” structure (such as “user registration flowchart: 5 steps”) can improve operation success rate by 31%.

Diagrams in technical documents should include component names, such as “engine working principle diagram: labeled parts 1-5,” and this writing is adopted by engineering manuals at a rate of 72%.

Note that steps should be connected with arrows, do not use numbered lists.

​​Description Method​：

• Explain the diagram’s purpose
• Summarize key steps

​​Case Study​：

“Website building flowchart: requirement analysis → prototype design → front-end development → testing launch”

(3) Infographics

Social Media Examiner statistics show that infographics with ALT summarizing core viewpoints (such as “global social media user distribution: Asia accounts for 42%”) have a 33% higher sharing rate than detailed descriptions.

Health infographics need to include data sources, and those noting “WHO 2024 data” have a 45% higher credibility rating.

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

​​Optimization Strategy​：

• Summarize core viewpoints in ALT
• Provide detailed explanation in main text

​​Example​：

“Global carbon emission source distribution: energy production accounts for 42%, transportation 28%”

ALT Writing for Portraits and Scene Photos

(1) News Person Photos

Associated Press guidelines require portrait photo ALT to include “name + title + scene,” and media that fully implement this have a 52% higher image citation rate. Academic conference photos should note “Professor Li from XX University speaking at 2024 AI Summit,” and this writing improves professionalism rating by 47%.

Avoid only writing vague descriptions like “expert group photo,” which reduces search visibility by 63%.

​​Five Elements​: person’s name + identity + location + time + action

​​Example​：”Professor Zhang Wei delivering keynote speech at 2024 Artificial Intelligence Conference”

(2) Team Photos

LinkedIn data shows that ALT text labeling team member count and identity (such as “XX Technology 2024 core team 10-person photo”) increases company page visits by 35%.

It is recommended to use “occasion + team + count” structure, such as “annual sales champion team 8-person award ceremony,” and this writing is adopted by HR departments at a rate of 68%.

Note not to list all members’ names, keep it concise.

​​Description Method​：Scene + person identity + count

​​Case Study​：

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

(3) Location Photos

TripAdvisor analysis shows that travel photo ALT containing seasonal features (such as “winter Jiuzhaigou snowscape”) has a 58% higher click-through rate than ordinary descriptions.

Architecture photos should note design style, such as “Gothic church spire close-up,” and this professional description increases收藏量 by 42.

It is recommended to use “location + feature + time” structure, avoiding subjective expressions like “beautiful scenery.”

​​Key Information​：

• Location name
• Prominent features
• Time (optional)

​​Example​：

“Shanghai Bund night view Oriental Pearl Tower lit state”

ALT Writing for Functional Images

(1) Navigation Icons

W3C accessibility testing shows that functional icon ALT using “action + element” structure (such as “search button”) achieves 98% screen reader recognition accuracy.

Shopping cart icons are recommended to consistently use “view shopping cart” rather than “shopping basket,” and this standardized expression increases conversion rate by 15%.

Avoid using vague instructions like “click here,” which increases operation confusion by 42%.

​​Description Principle​：Function + element type

​​Example​：

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

(2) Social Media Icons

Hootsuite research shows that social icon ALT using “platform + function” format (such as “Twitter share button”) can increase click-through rate by 23%.

It is recommended to consistently use official platform names, such as “LinkedIn” rather than “领英,” and this consistency increases brand recognition by 37%.

Note that different platform icons need independent ALT, cannot uniformly use “social icon.”

​​Naming Standard​：Platform name + icon

​Case Study​：

“Facebook homepage link icon”

(3) Button Images

Baymard Institute research finds that action button ALT containing action verbs (such as “buy now”) has a 29% higher conversion rate than static descriptions (such as “red button”).

Key buttons are recommended to use first person, such as “my orders” has a 17% higher click-through rate than “user orders.”

Avoid using redundant expressions like “click submit,” keep it concise and powerful.

​​Writing Key Points​：Action description + button

​​Example​：

• “Buy now button”
• “Member registration button”

​​Recommended Practical Tools​：

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

​​Common Mistake Correction Table​：

Mistake Type	Wrong Example	Correction Plan
Too brief	“Photo”	“Team discussing project plan in conference room”
Keyword stuffing	“phone smartphone 5G phone new model”	“Huawei Mate60 Pro 5G phone Yachuancing color”
Ignoring functional images	Search icon has no ALT	“Site search button”

​5 Common ALT Writing Mistakes

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

WebAIM research indicates that product images with ALT text errors on e-commerce websites have a 29% lower conversion rate than those with optimized ALT text.

Images using default filenames (such as IMG_001.jpg) have an 83% probability of being filtered by Google image search.

Here are the five most common ALT text mistakes:

1. ​​Keyword Stuffing​：Causes search ranking decline of 15-20%
2. ​​Overly Brief Descriptions​：User bounce rate increases by 42%
3. ​​Ignoring Functional Images​：Violates WCAG 2.1 accessibility standards
4. ​​Using Same ALT Text​：Judged as low-quality content
5. ​​Relying on AI Auto-generation for ALT​：Accuracy rate less than 35%

Mistake 1: Keyword Stuffing

(1) Specific Manifestations

Google Search Console data shows that keyword stuffing ALT text accounts for approximately 23% of problem images, mainly manifesting as the same keyword repeated more than 3 times (such as “phone smartphone 5G phone”).

Amazon platform review found that this type of non-compliant ALT results in a 47% probability of product images being filtered.

Typical characteristics include: using more than 5 keywords, repeating brand names (such as “Nike Nike shoes NIKE”), adding irrelevant promotional words (“discount sale free shipping”).

• Filling ALT with multiple unrelated keywords
• Repeating the same keyword multiple times

​​Example​：

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

(2) Negative Impact

SEMrush experiments show that keyword stuffing ALT text causes image search ranking to decline by an average of 18 positions. Screen reader testing shows that this type of ALT leads to a 62% comprehension error rate, with users needing an additional 15 seconds to identify effective information.

Google algorithm will mark this behavior as “over-optimization,” reducing the entire page’s E-E-A-T score by 23%.

• Google may judge it as cheating behavior
• Image search ranking drops by 15-20%
• Poor screen reader user experience

(3) Correction Method

Ahrefs recommends using “brand + core attribute + differentiated selling point” structure, such as “Adidas Ultraboost running shoes black energy-return midsole.”

Tests show that this writing with naturally included 1-2 keywords not only increases search visibility by 35% but also maintains 98% accessibility compliance rate.

The key is to ensure every modifier has actual meaning, avoiding filling with ineffective words.

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

​​Corrected Example​：

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

Mistake 2: Overly Brief Descriptions

(1) Common Cases

WebAIM survey indicates that 42% of websites have the problem of ALT text being too brief, with ineffective descriptions like “image,” “icon,” etc. accounting for the highest percentage (37%). In e-commerce, 23% of product images only label product category names (such as “dress”), preventing Google from identifying specific products.

Among news websites, 19% of accompanying images use vague expressions starting with “image shows…”

• Only writing “image,” “photo,” “chart”
• Product images only write category name

​​Example​：

❌ “phone”

❌ “meeting photo”

(2) Data Impact

For images with brief ALT text on mobile first screen loading, user skip probability reaches 58%. When screen reader users encounter such images, 73% choose to leave the page directly.

This type of ALT causes 41% loss in image search traffic, missing numerous long-tail keyword opportunities.

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

(3) Optimization Plan

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

For example, optimize “phone” to “photographer using iPhone 15 Pro shooting aurora landscape.”

• Supplement key attribute information
• Reach 80-125 character length

​​Optimized Example​：

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

Mistake 3: Ignoring Functional Images

(1) Typical Scenarios

WAVE detection report shows that 85% of websites have the problem of missing functional image ALT, with search icons (62%), shopping carts (58%), and social sharing (49%) ranking in the top three.

• Navigation menu icons without ALT
• Form submit buttons without descriptions
• Social media icons not labeled

​​Example​：

❌ Search icon using alt=””

(2) Correct Writing

W3C recommends using verb structure of “action + object,” such as “expand menu button,” “submit order button.” For social icons, should note “jump to [platform],” such as “jump to Twitter page icon.”

• Describe the function of buttons/icons

​​Corrected Example​：

✅ “Site search button”

✅ “Facebook homepage link icon”

Mistake 4: Using Same ALT for All Images

(1) Common Situation

38% of e-commerce websites have the problem of multiple images with the same ALT, with clothing products (color/style differences) accounting for the highest percentage (47%).

Among content websites, 28% of accompanying images use batch-copied ALT text.

This lazy practice causes Google to judge 75% of duplicate ALT images as “low-value content.”

• Multi-angle product images using the same ALT
• Article images batch-copying ALT

​​Example​：

❌ Three different angle watch images all using “watch display”

(2) SEO Impact

Google image search will categorize images with the same ALT as duplicate content, reducing visibility by 40%. Tests show that writing differentiated ALT for multi-angle product images (such as “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 by Google as low-quality content
• Image search visibility decreases by 40%
• Missing long-tail keyword opportunities

(3) Solution

It is recommended to establish an ALT template system: product main images use “brand + model + parameters,” detail images add “close-up” suffix (such as “lens coating close-up”), scene images note usage environment (such as “outdoor hiking scene”).

Amazon top sellers’ data shows that systematic writing achieves 98% ALT uniqueness rate.

• Write unique ALT for each image
• Distinguish shooting angles and focuses

​​Correct Examples​：

1. “Watch front wearing effect”
2. “Dial scale detail close-up”
3. “Strap buckle structure display”

Mistake 5: Relying on Auto-generated ALT

(1) Main Problems

MIT research shows that CMS auto-generated ALT text accuracy rate is only 31%, with common errors including: misidentifying subjects (28%), missing key information (39%), using generic words (33%).

In WordPress media library default ALT, 47% are ineffective naming like “image123.”

• CMS auto-generated ALT has low accuracy
• Frequently appearing “image,” “photo” and other ineffective words

​​Example​：

❌ “image_20240815_01”

(2) Quality Data

Comparative testing shows that manually optimized ALT has a 63% higher search click-through rate than auto-generated versions, and user dwell time is 42 seconds longer.

Incorrect auto ALT may cause misinformation, such as identifying “diabetes tester” as “thermometer,” with medical field misidentification rate as high as 15%, posing significant risks.

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

(3) Improvement Measures

It is recommended to adopt “AI initial screening + manual verification” mode: first use tools like Adobe Sensei to generate drafts, then have editors supplement professional details.

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

• Manually review image ALT
• Set auto ALT generation rules
• Use AI auxiliary tools (requires manual verification)

​​Optimization Effect Comparison Table​：

Mistake Type	Pre-correction CTR	Post-correction CTR	Improvement
Keyword stuffing	1.2%	2.8%	+133%
Brief descriptions	1.5%	3.1%	+107%
Same ALT	1.8%	3.6%	+100%

Start optimizing now, and let every image create more possibilities for your website!