SEO Alt Text: The 2026 Best-Practices Guide

What alt text actually is

The alt attribute on an <img> tag is a text alternative shown when the image can't load, read aloud by screen readers, and used by search engines to understand image content. Google confirms it uses alt text as a primary signal for Google Images and as a secondary signal for ranking the page overall.

The 12 rules that matter

Follow these and you'll outrank 90% of sites competing for the same image queries:

• Describe the image, don't summarize the page. Focus on what's visually there.
• Keep it under 125 characters. Most screen readers cut off around that length.
• Include the target keyword once, naturally — never keyword-stuff.
• Never start with 'Image of' or 'Picture of' — screen readers already announce it.
• Use empty alt (alt="") for purely decorative images so screen readers skip them.
• Match alt text to search intent. A product photo's alt should read like a product search query.
• Include text that appears inside the image (a headline in a hero banner, a chart title).
• For infographics, use alt text as a short summary + link to a longer transcript.
• Localize alt text if you serve multiple languages — it's a ranking signal per-locale.
• Never duplicate alt text across a page — every image needs a unique description.
• Filename matters too. `red-nike-air-max-90.jpg` beats `IMG_2847.jpg`.
• Pair alt text with a descriptive caption when possible — captions get ~2x the read rate of body copy.

Real examples

Bad: 'shoe'. Better: 'red running shoe'. Best: 'Red Nike Air Max 90 running shoe on a wooden floor'. The best version is specific, includes brand + product + context, and reads naturally to a screen reader.

The fastest way to do this

AltPixel auto-generates SEO-optimized alt text using vision AI, following every rule above. Drop your image, get a copy-paste-ready alt tag in under 3 seconds.