Reference table
How many interviews: sample size by project type
A quick guide to choosing the number of qualitative interviews
A decision table for choosing how many qualitative interviews to run. It matches four project types, from a quick discovery sprint to foundational research, with the kind of population, the recommended number of interviews and the reasoning. Use it to set a starting sample, then watch for saturation as you go.
Where this appears
What's in this reference table
| Project type | Population | Interviews | Why |
|---|---|---|---|
| Quick discovery sprint | Homogeneous, focused topic | 5 to 8 | Surface top themes quickly; time-boxed |
| Standard product research | Moderately homogeneous | 8 to 12 | Reach code saturation with good confidence |
| Deep strategic research | Diverse or complex population | 12 to 20 | Approach meaning saturation for nuanced understanding |
| Foundational research | Highly diverse, new domain | 20 to 30 | Map a wide landscape; build comprehensive understanding |
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<a href="https://www.koji.so/visuals/how-many-interviews-sample-size-by-project-type"><img src="https://www.koji.so/visuals/how-many-interviews-sample-size-by-project-type/how-many-interviews-sample-size-by-project-type.png" alt="Table of interview counts by project type, from 5 to 8 for a discovery sprint to 20 to 30 for foundational research, with population and reasoning." width="1200" height="769" /></a>
<p>Source: <a href="https://www.koji.so/visuals/how-many-interviews-sample-size-by-project-type">How many interviews: sample size by project type</a>, Koji</p>
