AI Image Alt Text: Writing Better Descriptions
Alt text is a short description of an image that screen readers read aloud, that appears when an image fails to load and that helps search engines understand your page. Writing it well is one of the simplest ways to make a site more accessible. AI image alt text tools can generate descriptions in seconds, which is a great help when you have hundreds of images, but the results are often too generic, too long or simply wrong. This guide explains what good alt text looks like, how to use AI to draft it, how to review the results, special cases such as charts and logos and a quick routine for busy site owners.
Why alt text matters
People who are blind or have low vision often use screen readers that read the alt text instead of showing the picture. Without it, they may hear only a file name or the word image, and miss important information. Alt text also helps people on slow connections, users with images turned off and search engines that cannot see pictures. In many places, accessibility is also a legal or contractual requirement for public and commercial sites. For wider context, see AI accessibility tools: helping everyone use the web.
What good alt text looks like
- Describe the purpose, not only the content. Ask what the image adds to the page, and describe that.
- Be concise. A short phrase or one or two sentences is usually enough, and long descriptions belong in the page text.
- Be specific. A golden retriever catching a red frisbee in a park is better than a dog.
- Skip redundant words. Screen readers already announce that it is an image, so avoid starting with image of or picture of.
- Include text shown in the image. If a banner says Summer Sale 20 percent off, include those words.
- Use natural language. Do not stuff keywords; it hurts both accessibility and trust.
- Match the context. The same photo may need different alt text on a news page and on a product page.
Special cases
- Decorative images: if an image adds nothing, such as a divider or background texture, use an empty alt attribute so screen readers skip it.
- Linked images: describe where the link goes, such as Download the pricing guide, not the picture.
- Logos: use the company name, such as Example Co home, if it links to the home page.
- Charts and graphs: give a short summary in the alt text, such as Line chart showing sales rising from 100 to 180 between January and June, and provide the full data in a table or text nearby.
- Screenshots: explain what the viewer needs to know, and describe key labels.
- Product photos: include color, type and details that influence a purchase; see AI product descriptions for online stores.
- People: describe relevant actions and context, and use names only when you know them and it matters.
How to use AI for alt text
- Give context. Tell the AI where the image will appear, what the page is about and what the reader needs from the image.
- Ask for a short description. For example: write alt text of under 125 characters for this image on a recipe page, focusing on the finished dish.
- Ask for alternatives. Compare two or three, and choose the one that best fits the page.
- Review every one. AI can misidentify objects, invent details or miss the point of the image.
- Add what only you know. Names, places, product details and the purpose are your responsibility.
- Keep a list. Save your decisions in a spreadsheet for later updates.
Remember that AI descriptions can contain errors for the same reasons as other AI text; see AI hallucinations: why they happen.
Check for common problems
- Descriptions that are too vague, such as photo or graphic.
- Guesses about people’s age, gender, emotions or ethnicity that the image does not support.
- Missing text in the image.
- Different alt text for repeated images on one page, which adds noise.
- File names such as IMG_4821.jpg used as alt text.
- Overlong descriptions that read like a paragraph.
Alt text and SEO
Descriptive alt text can help images appear in image search and gives context to your page. But accessibility should come first. Write for the person who cannot see the picture, and include a keyword only when it naturally belongs. Do not repeat the same phrase across many images. For overall guidance on responsible optimization, see AI for SEO: how to use it without hurting your rankings, and for business pages, local SEO and AI: small business basics.
A quick routine for busy sites
- Run a report to find images without alt text.
- Fix the most important pages first: home, services, products and top blog posts.
- Use AI to draft, and a person to edit.
- Mark decorative images with an empty alt attribute.
- Check new images before publishing.
- Test a page with a screen reader or a keyboard-only session if you can.
A worked example
A bakery site has a photo of a tray of cinnamon rolls on its menu page. The auto-generated alt text says food on a table. The owner asks AI for a better version, giving the context: a menu page for freshly baked goods. The draft reads: tray of eight cinnamon rolls with white icing, fresh from the oven. She checks the photo, sees that there are six rolls, fixes the count and keeps the shorter version. A visitor using a screen reader now knows what the picture shows, and the page also gains useful context.
Frequently asked questions
How long should alt text be?
Usually under about 125 characters, though complex images may need a short summary plus a longer description nearby.
Do I need alt text for every image?
Every informative image needs it. Decorative images should have an empty alt attribute.
Can I rely on automatic alt text from my platform?
Use it as a draft, and review it, since errors are common.
