What alternate text is
Alternate text (alt text) is a short written replacement for an image. Screen readers read it aloud in place of the image, and it is required for meaningful images by WCAG success criterion 1.1.1, Non-text Content. In a PDF it is stored on the image's Figure tag (W3C technique PDF1), which means the document has to be tagged for alt text to exist at all.
The easiest place to add it is in the source file before exporting: right-click an image in Word and choose View Alt Text, use Alt text in Google Docs, or Object Export Options > Alt Text in InDesign. In Acrobat Pro you can add or fix it in an existing PDF.
First decide what the image is for
The W3C's alt decision tree sorts images into a few kinds:
- Decorative: borders, background art, a repeated logo next to the body's name in text. Mark these as decorative (Word) or as artifacts (Acrobat, W3C technique PDF4) so screen readers skip them.
- Informative: a photo or simple diagram that adds information. Describe what it shows in a sentence or two.
- Functional: an image used as a link or button. Describe where it goes or what it does.
- Complex: charts, maps, site plans, organizational charts. Give a short alt text and put the full information in the text of the document.
Examples for common packet images
These examples are invented for illustration.
| Image | Suggested alt text |
|---|---|
| Village seal beside the heading "Village of Sampleton" | Mark as decorative: the name is already in the text. |
| Location map for a zoning case | Map showing the 2.3-acre parcel at the northeast corner of Main Street and 3rd Street, outlined in red. Nearby: the library to the west and homes to the north. |
| Site plan for a building addition | Site plan for the proposed library addition. The layout is described in the staff report on pages 4 to 6. |
| Bar chart of water fund revenue | Bar chart: water fund revenue rose from $1.2 million in 2024 to $1.5 million in 2026. (Put the yearly figures in a table next to the chart.) |
| Photo in a public works report | Pothole about three feet wide across the eastbound lane of Oak Avenue. |
| Scanned signature on a resolution | Signature of the Village President. |
| Organizational chart | Organizational chart of the public works department, described in the list below. |
Writing tips
- Keep it short. One or two sentences for most images. Longer information belongs in the body text.
- Say what matters here. The same photo might need different alt text in a staff report about road repairs and in a newsletter about a volunteer day.
- Skip "image of" and "picture of". Screen readers already announce that it is an image.
- Include any text in the image, such as the words on a sign or a chart title.
- Never use the file name. "IMG_2034.JPG" or "image1.png" tells the listener nothing. PacketReady flags alt text that looks like a file name or a placeholder.
- Review automatic descriptions. Office can suggest alt text automatically. Suggestions such as "A picture containing text, description automatically generated" are a starting point at best.
Charts, maps and plan sets
A chart's alt text can state the main point, but the numbers should be in a table or in the text so everyone can use them. For maps in zoning and planning cases, describe the location in words (streets, direction, landmarks, size) in the staff report itself. Engineering drawings and large plan sets rarely become fully accessible; a written summary of what the plans show, and a contact for questions, makes the information available.
Checking alt text
Automated tools can confirm that each Figure tag has alternate text and can catch obvious placeholders, but they cannot tell whether a description is accurate or helpful. PacketReady lists how many images lack alt text and shows a sample of the descriptions it found, so you can read them. For a full review, listen to the document with a screen reader such as NVDA or inspect each Figure tag in Acrobat Pro's Tags panel.
Check your own files
PacketReady checks a whole packet folder in your browser, with nothing uploaded, and explains every fix in plain English.
Related guides: Tagged PDF, explained ยท How to check a PDF