How many interviews do you need to build a good persona?

• If you don’t have a good first guess: Cast a wide net and have many short (15 minute) conversations with many more people (30-50) to help you come up with a tighter target.
• Once you have a tight target: Interview 20-30 for each unique persona
• For B2B you will need to interview many people with the same role per company as you will be able to get into many fewer companies than 20-30. 

Special thanks: Martin Trust Centre, MIT

Edit: Javier Rojas, 06/05/20