Article · About a 10 minute read

Why You Only Need to Test with 5 Users

Jakob Nielsen · Nielsen Norman Group Free Beginner

This is the piece that gives you permission to stop waiting for a big study. Nielsen shows that just five people uncover roughly 85 percent of the usability problems in your app, and that running several small tests beats one large one because you can fix things between rounds. For a founder with no budget, it reframes testing from a scary research project into something you can do this week.

  • Five users find about 85 percent of usability problems, so you do not need a large sample to learn what is broken
  • Running three small tests and fixing between them beats a single big study
  • The rule holds for qualitative testing of a fairly similar user group, so split into small groups if your users are very different
Open on nngroup.com ↗

It answers 5 questions

  1. How do I know if my product is confusing to users?
  2. Why does good design actually matter for an early-stage startup?
  3. How do I show a prototype to users without biasing their reaction?
  4. How do I run a quick usability test on my app when I don't have a budget or a research team?
  5. How do I turn vague feedback like "the app feels clunky" into specific design changes I can actually make?

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