PDF How To: Add Alternative Text

Why do I need to add alternative (alt) text?

Alt text gives screen readers the words to describe your images and helps keyboard users who tab through your content—when they land on an image, they’ll hear (or see) its description. Without alt text, images get skipped or announced by their file names, which can be confusing.

What counts as alt text?

Informative images (charts, photos, diagrams) need a short description that conveys their purpose.
Decorative images that don’t add meaning (borders, spacers) should be marked “decorative” so screen readers ignore them.

Word

Right-click (or Ctrl-click) the image and choose Format Picture.
In the sidebar, expand Layout & Properties, then Alt Text.
In the Title field, enter a short name (optional).
In the Description field, type your alt text.

InDesign

Use the Selection tool to click the image.
Go to Object > Object Export Options.
Click the Alt Text tab.
From Type, choose Custom and enter your text.

Adobe Acrobat Pro

Open Tools > Accessibility > TouchUp Reading Order.
Click the image:
If it’s meaningful, choose Figure.
If it’s decorative, choose Background and skip to step 5.
Right-click (or Ctrl-click) the image and select Edit Alternate Text.
Type your alt text (or mark for decorative).
Click OK.
Run Accessibility Check. Note: If a decorative image still flags, reopen Edit Alternate Text and ensure it has "".

Recommendations

Follow these best practices when writing alt text:

Be accurate and equivalent: Convey the same information the image provides.
Be succinct: Keep it short, usually under 125 characters.
Avoid redundancy: Don’t repeat nearby text.
Skip “image of…” or “graphic of…”: Screen readers already announce it’s an image.

Additional Resources:

One Stop: Core Topic Alt Text

WebAIM: Alt Text Introduction

Social Security Administration: Alt Text Guide pdf