How to Write Alt Text for SEO and Accessibility
Guide · SEO Tools
Alt text is a short description attached to an image in the HTML, read aloud by screen readers and shown if the image fails to load. It exists first for accessibility — letting a blind or low-vision user understand what an image shows — and it happens to help image search and overall page context as a secondary benefit.
What makes alt text actually good
- Describes what matters — not just "image" or the filename, but what's actually in the photo and why it's there.
- Specific over generic — "black leather laptop bag with brass buckle" tells a screen reader user something useful; "bag" does not.
- No keyword stuffing — cramming multiple search terms into alt text reads as spam to both screen readers and search engines, and actively hurts the accessibility purpose it's supposed to serve.
- Skip "image of" or "picture of" — screen readers already announce that it's an image; restating it is redundant.
Good vs bad examples
| Bad | Good |
|---|---|
| alt="IMG_4821.jpg" | alt="Blue ceramic mug with hand-painted floral pattern" |
| alt="image" | alt="Golden retriever puppy sitting in autumn leaves" |
| alt="mug coffee mug ceramic mug handmade mug gift mug" | alt="Handmade ceramic coffee mug, cream glaze, 12oz" |
When alt text should be empty
Purely decorative images — a background pattern, a spacer graphic, a repeated design flourish that carries no actual content — should have empty alt text (alt=""), not a forced description. A screen reader will correctly skip past an empty alt attribute; leaving it out entirely, on the other hand, sometimes causes the screen reader to read the filename aloud instead, which is worse.
Writing alt text at scale
For a shop or blog with dozens of product photos, writing genuinely descriptive alt text for each one individually is tedious but worth doing properly rather than copy-pasting the same generic phrase everywhere. Use the Alt Text Helper to check draft alt text against length and clarity guidelines before publishing.