How to Add Text Equivalents for Diagrams, Tables, and Screenshots

Text equivalents are the written forms of visual content. They allow people who cannot see an image clearly, or who are reading a document through assistive technology, to get the same information in another format. In accessibility writing, text equivalents are not optional decoration. They are part of how content becomes usable.

The need is practical, not abstract. A diagram may explain a process, a table may hold the key data in a report, and a screenshot may show an interface state or error message. If those visuals are not described well, the document loses meaning for many readers. Text equivalents also help search, indexing, translation, and AI parsing, because machines can process structured text more reliably than embedded images.

This article explains how to write useful text equivalents for diagrams, tables, and screenshots, with a focus on clarity, accuracy, and brevity.

Essential Concepts

• A text equivalent conveys the same function and information as the visual.
• Write for the purpose of the image, not every detail.
• Diagrams need concise summaries plus key relationships.
• Tables need semantic structure, not image-style descriptions.
• Screenshots need text for visible text, state, and relevant context.
• Keep wording plain, specific, and readable by screen readers and AI parsing tools.

Why Text Equivalents Matter

A visual can support understanding in different ways. Sometimes it gives a quick overview. Sometimes it provides exact values. Sometimes it proves what a screen looked like at a given moment. A text equivalent should match that role.

For accessibility writing, the main goal is not to describe every pixel. The goal is to preserve meaning. If a chart shows a trend, the text equivalent should explain the trend. If a table compares products, the text equivalent should preserve the comparison. If a screenshot shows an error message, the text should identify the message and the context.

Text equivalents matter for at least four reasons:

1. They support screen reader users.
2. They help readers with low vision, cognitive load, or broken images.
3. They improve reuse in documents, reports, and knowledge bases.
4. They make content easier for AI parsing and search systems to interpret.

The same principle applies across formats: describe the function first, then the content that supports it.

General Principles for Writing Text Equivalents

Before getting into diagrams, tables, and screenshots, it helps to use a few shared rules.

Start with the purpose of the visual

Ask: Why is this here?

• To explain a process
• To compare data
• To show a screen state
• To provide evidence
• To support a point in the surrounding text

The answer determines the text equivalent. A diagram that explains a workflow needs a summary of the sequence. A screenshot of an error page needs the message, not a transcript of all navigation elements.

Be concise, but not vague

Too little detail creates confusion. Too much detail buries the main point.

Weak example:

• “An image showing a chart with some bars.”

Better:

• “Bar chart showing sales rising steadily from January to June, with a sharp peak in May.”

Avoid visual language that does not translate

Phrases like “on the left,” “in the corner,” or “the big blue area” are not useful unless spatial arrangement is part of the meaning. Prefer functional language:

• “The first column lists departments.”
• “The callout indicates the approval step.”
• “The alert message appears above the form.”

Keep terminology consistent

If a document uses “customer account,” do not switch to “user profile” for the same item. Screen readers, translators, and readers alike benefit from stable language.

How to Add Text Equivalents for Diagrams

Diagrams include flowcharts, architecture maps, timelines, org charts, network diagrams, and process illustrations. Their job is usually to show relationships or sequence, not exact measurements. The text equivalent should follow that same logic.

1. Identify the diagram type and function

Different diagrams need different treatments.

• Flowchart: Explain the steps and decision points.
• Timeline: List events in order.
• Org chart: Name the reporting structure.
• System architecture diagram: Summarize components and connections.
• Concept map: State the main ideas and how they relate.

2. Write a brief summary first

Start with one sentence that explains the point of the diagram.

Examples:

• “Flowchart showing the steps for submitting a travel request and routing it for approval.”
• “Network diagram showing a user device connecting to a web server, database, and authentication service.”
• “Timeline showing major revisions to the policy between 2021 and 2024.”

3. Describe the key relationships or steps

After the summary, list the important parts in order. Do not try to recreate every graphic element unless it matters.

Example text equivalent for a process diagram:

Text equivalent:

• Start: Employee completes request form.
• Next: Manager reviews request.
• If approved, the request goes to finance.
• If rejected, the employee receives a notice.
• Final step: Finance issues reimbursement.

This style works well because it gives the sequence directly, which is often how the information is used.

4. Include decision points and outcomes

In a diagram, arrows and branches often matter more than labels. Make those explicit.

Example:

• “If the application is complete, it moves to review. If required fields are missing, the applicant is prompted to revise and resubmit.”

5. Use longer descriptions when the diagram is dense

Some diagrams cannot be captured in a single sentence. In those cases, a short alt text can be paired with a longer text description nearby or in an appendix.

Example:

Short text equivalent:
“System diagram showing a website, payment gateway, and database exchanging data during checkout.”

Longer description:
“The website sends order details to the payment gateway. After payment authorization, the gateway returns a success code to the website. The website then writes the order record to the database and sends a confirmation email to the customer.”

Diagram example

Suppose a diagram shows this process:

1. Customer submits a support ticket
2. Support team triages the ticket
3. Urgent issues go to engineering
4. Other issues receive a response from support
5. Ticket closes after resolution

A useful text equivalent would be:

“Flowchart showing a support ticket process: customer submission, triage by support, escalation of urgent issues to engineering, direct response for other issues, and closure after resolution.”

That version is concise, readable, and faithful to the diagram’s function.

How to Add Text Equivalents for Tables

Tables are different from diagrams because they carry structured data. A table text equivalent should preserve that structure. Often, the best text equivalent is not a full prose description of every cell. It is a proper semantic table with clear headers, followed by a short summary if needed.

1. Use actual table markup whenever possible

If you are writing in HTML, Word, Markdown, or another format that supports real tables, use the structure rather than turning the data into an image. Semantic markup helps screen readers and AI parsing understand rows, columns, and headers.

A simple Markdown table:

Department	Budget	Change from Last Year
Operations	$120,000	+8%
Marketing	$90,000	-3%
IT	$150,000	+12%

This table already serves as a text equivalent if it is structured correctly.

2. Add a concise summary for the table’s main point

A table often needs a brief sentence before or after it. This helps readers understand why the data matters.

Example:

• “The IT department has the highest budget and the largest year-over-year increase.”

That line does not replace the table. It gives context.

3. Preserve row and column relationships

Readers need to know what each cell means. Do not flatten a table into a long paragraph unless the table is very small or the format cannot support markup.

Poor approach:

• “Operations budget 120000 change 8 percent marketing budget 90000 change minus 3 percent…”

Better approach:

• Keep the table intact and add a short summary.

4. Explain unusual table structures

Some tables have merged cells, grouped headers, or footnotes. In those cases, the text equivalent should explain the structure clearly.

Example:

• “The table compares quarterly revenue across three regions. The first header row groups columns by quarter, and the second row lists revenue by product line.”

5. Include units, time frames, and exceptions

Numbers without units can be misleading. A table with “Revenue” should say whether the values are in dollars, euros, or thousands. A table with dates should identify the date range.

Table example

If a table lists project milestones:

Milestone	Owner	Due Date
Draft scope	Project lead	March 4
Review draft	Legal	March 11
Final approval	Director	March 18

A good text equivalent is:

“Project milestone table showing three steps: draft scope by the project lead on March 4, legal review on March 11, and final approval by the director on March 18.”

This preserves the structure and the key sequence.

How to Add Text Equivalents for Screenshots

Screenshots often show software interfaces, web pages, forms, notifications, or visual evidence of a state. The challenge is that a screenshot may contain both text and layout. The right text equivalent depends on why the screenshot is included.

1. Decide whether the screenshot is informational or evidentiary

Ask whether the screenshot is there to show:

• a button or menu location
• an exact message
• a completed state
• a user workflow
• an error condition
• a design example

If the screenshot is only decorative, it should probably not be there at all.

2. Transcribe meaningful visible text

If the screenshot contains important words, those words should appear in the text equivalent, especially if the screenshot is the only source of that information.

Example:

• “Error message: ‘Your session has expired. Please sign in again.’”

That is better than:

• “Screenshot of an error page.”

3. Describe the interface state

Screenshots often need context beyond visible text. Mention what screen it is and what state it shows.

Examples:

• “Screenshot of the account settings page with the Security tab open.”
• “Screenshot of the checkout page showing an invalid credit card entry.”
• “Screenshot of the dashboard after a successful login.”

4. Include only relevant interface elements

A screenshot may contain a navigation bar, logo, footer, and several buttons. Not all of that matters.

If the screenshot supports a guide to changing a password, the relevant elements are probably:

• the page title
• the password fields
• the submit button
• any validation message

The logo or footer usually does not need to be described unless it matters to the purpose.

5. Use captions and nearby text to reduce repetition

If the surrounding text already explains the screenshot, the text equivalent can be short and focused. Repeating the same explanation in multiple places is unnecessary.

Example caption:

• “Figure 3. Settings page with notifications enabled.”

Possible alt text:

• “Screenshot of the settings page showing notifications turned on.”

Screenshot example

Suppose a screenshot shows this interface state:

• Title: “Reset Password”
• Fields: “Email address,” “New password,” “Confirm password”
• Button: “Save changes”
• Message: “Password must be at least 12 characters.”

A useful text equivalent would be:

“Screenshot of the Reset Password page with fields for email address, new password, and confirm password, plus a Save changes button and a notice that passwords must be at least 12 characters.”

This gives the reader the relevant text and the state of the interface.

Writing for Accessibility and AI Parsing at the Same Time

Good text equivalents help humans first, but they also support systems that extract, index, translate, or summarize content. Clear structure matters.

For better AI parsing:

• use real headings
• label tables with proper headers
• keep diagram descriptions sequential
• write screenshot text in complete, plain sentences when possible
• avoid ambiguous references like “this” or “that button” without context

Structured text is easier to process than a visual file with no description. That does not mean writing for machines should replace writing for people. It means readable prose and clean structure serve both.

Common Mistakes to Avoid

Describing appearance instead of meaning

Do not stop at color, shape, or position unless those details carry the message.

Weak:

• “Blue box on the right with arrows.”

Better:

• “Decision point showing that approved requests move to finance.”

Repeating the surrounding caption

If the caption already says “Revenue by quarter,” the text equivalent does not need the same phrase three times. Add the information the caption does not provide.

Copying every word from a busy screenshot without context

A long transcript of a screen can be hard to use. Focus on the important text and the state of the interface.

Turning a table into a paragraph of numbers

That often makes the data harder to understand. Preserve structure when possible.

Leaving out the conclusion of a diagram

If a process ends in approval, rejection, or escalation, state that. Readers need the full logic.

A Simple Workflow for Creating Text Equivalents

A reliable process helps keep text equivalents consistent.

Step 1: Identify the purpose

What does the visual do in the document?

Step 2: Choose the right form

• short alt text
• long description
• structured table
• caption plus summary

Step 3: Extract the essential information

Include the names, numbers, steps, and outcomes that matter.

Step 4: Edit for clarity

Remove redundancy, vague language, and visual references that do not help.

Step 5: Test the result

Read it without looking at the visual. Ask:

• Does it still make sense?
• Does it preserve the key meaning?
• Would someone understand the same point?

Practical Examples

Example 1: Diagram in a training guide

Visual: a flowchart for submitting expense reports.

Text equivalent:

• “Flowchart showing the expense report process: employee submits report, manager reviews it, finance checks receipts, and approved expenses are reimbursed.”

Example 2: Table in a report

Visual: a table comparing three software tools across cost, support hours, and storage limits.

Text equivalent:

• “Comparison table showing that Tool A has the lowest cost, Tool B offers the most support hours, and Tool C provides the largest storage limit.”

Example 3: Screenshot in a help article

Visual: a screenshot of a settings page with a toggle turned off.

Text equivalent:

• “Screenshot of the Notifications settings page with email alerts turned off.”

These examples show the same pattern: identify the purpose, then state the important content directly.

FAQ’s

What is the difference between alt text and a text equivalent?

Alt text is one kind of text equivalent. It is usually short and attached to an image. A text equivalent is the broader idea, which can include alt text, captions, long descriptions, transcripts, or structured tables.

How long should alt text be?

Long enough to convey the point, short enough to stay readable. For many images, one sentence is enough. For complex diagrams or screenshots, a short alt text plus a longer nearby description may work better.

Should I describe every detail in a diagram?

No. Describe the parts that matter to the purpose of the visual. If a color, label, or icon changes the meaning, include it. Otherwise, leave it out.

Do tables need alt text?

If a table is real text and properly structured, the table itself is the text equivalent. A brief summary may still help. If the table is an image, it needs a proper textual version of the data.

What if a screenshot contains a lot of text?

Include the important text and the reason the screenshot is there. If the full text matters, provide a transcript or a nearby written summary. Do not force all context into a short alt attribute.

How do text equivalents help AI parsing?

They make content machine-readable. Clear labels, structured tables, and direct descriptions help systems extract meaning more reliably than unannotated images.

Conclusion

Text equivalents make visual content usable beyond sight. For diagrams, summarize the process or relationship. For tables, preserve structure and add context. For screenshots, capture the visible text and the relevant interface state. The best text equivalents are accurate, concise, and shaped by purpose. In accessibility writing, that is the standard that matters.