Miller's Law

What is it?

Miller's Law comes from George Miller's 1956 paper 'The Magical Number Seven, Plus or Minus Two,' which established that the average human working memory can hold 7±2 items (chunks) simultaneously. Crucially, a 'chunk' can be a digit, a word, or any coherent unit of information. This means that how you structure information is as important as how much information you present.

Why it matters

When you present more than 7 items in a list, navigation, or set without chunking, you exceed most users' working memory and force them to rely on external memory aids — scrolling back, re-reading, or guessing. Chunking and limiting choices is not about dumbing things down; it's about working with memory instead of against it.

Best Practices

• Limit top-level navigation items to 7 maximum. 5 is better.
• Group long lists into categories of 5–7 items each.
• Phone numbers are formatted in chunks (555-867-5309) for exactly this reason — copy the principle.
• Break long forms into sections of 5–7 fields each.
• Dashboard cards: show a maximum of 7 KPI metrics at once.
• Use visual chunking (borders, whitespace, headings) to create psychological groups that stay within memory limits.
• For product listings, paginate or use "load more" rather than infinitely extending a single list.
• Seven options in a dropdown is fine. Seventeen requires a search.
• Remember that "chunks" can be complex — a labeled icon counts as one chunk, not two.

Common Mistakes

• Navigation menus with 10+ items at the same level.
• Forms with 20 visible fields with no visual grouping.
• Dashboard overload: 15+ cards with no visual hierarchy.
• Long dropdowns with 50+ options and no search.
• Feature lists presented as flat, undifferentiated bullet lists of 20 items.
• Overwhelming users with all account settings on a single unstructured page.

Checklist

Research & Theory

Real-World Examples