Miller’s Law

Miller’s Law suggests that the average number of objects an individual can hold in their working memory is 7 ± 2. In UX design, this means that users can process only a limited amount of information at once. Designers can use this principle to break up information into smaller chunks (e.g., using bullet points, short paragraphs, and clear categories) to avoid overwhelming users.

Miller's Law is the scientific backing for chunking information in UI — breaking long strings (phone numbers into 3-4 digit groups, credit card numbers into groups of 4) makes them dramatically easier to process and verify. For SaaS product teams, it argues for limiting navigation items to 7 or fewer, breaking long forms into steps, and grouping settings into logical clusters rather than presenting a single overwhelming list.

Phone number fields format numbers as you type (555-867-5309 rather than 5558675309) specifically because of Miller's Law — the grouped format reduces cognitive load for verification and error-checking by breaking a 10-digit string into three memorable chunks.