Customers & Research

How many customer interviews do I need before I trust the job I've found is real?

A starting point

There's no magic number, but the honest signal is repetition: when your last three interviews stop surprising you and start confirming the same struggle, you're close. Most founders stop at five when the real jobs surface around interview ten to fifteen, because the early ones teach you how to ask better. As a starting point, keep going until a new interview no longer changes your mental model of the job.

Go deeper

Hand-picked from around the web, each with a note on why it earns your time.

3 resources 3 link-checked Watch Read

Watch

▶️ Video
✓ Link checked Free Intermediate

Why we picked it Reading about the switch interview is one thing, watching one run live is another. Bob Moesta and Chris Spiek interview an audience member on the spot about a real purchase, reconstructing the timeline of struggle from first thought to buy and mapping the forces that pushed and pulled them. It is the most concrete way to learn the actual questioning technique for uncovering the real job.

Uncovering the Jobs to Be Done (with a live switch interview)

On Business of Software by Bob Moesta and Chris Spiek

  • Build the buyer's timeline from the first thought to the purchase, so you surface the causality behind a switch instead of stated preferences
  • The forces diagram (push, pull, anxiety, habit) explains why someone moves or stays put, which matters most when your product is unfamiliar
  • Interview around a concrete recent decision, not hypotheticals, because memory of a real struggle is far more reliable than opinions about the future
Open businessofsoftware.org →

Read

📖 Book
✓ Link checked Paid Beginner

Why we picked it The single best thing ever written on customer conversations. It teaches you to ask about the customer's life and past behaviour, not your idea, so you can't be lied to. If a founder reads one thing before talking to a single customer, it's this.

The Mom Test

From momtestbook.com by Rob Fitzpatrick ~130 pages

  • Talk about their life, not your idea.
  • Ask about specifics in the past, not opinions about the future.
  • 'That's so cool, I'd totally buy it' is a compliment, not data, dig for commitment and evidence.
Open momtestbook.com →
✍️ Essay
✓ Link checked Free Beginner

Why we picked it The honest answer to 'how many' is not a magic number, it is saturation: you keep going until new interviews stop teaching you anything new. This piece explains that idea plainly and gives a workable starting point (begin with about 5 to 6, then continue until the themes stop shifting), which is exactly the judgment call a founder is trying to make. Treat it as a rule of thumb to sanity-check your gut, not a quota to hit.

Interview Sample Size in Qualitative UX Research

From Nielsen Norman Group (nngroup.com) by Maria Rosala ~10 min read

  • Saturation is the real stopping rule: when the same jobs and pains keep repeating and fresh interviews add nothing, you can trust the pattern.
  • Start small (roughly 5 to 6) for a focused, similar group, and add more the moment answers start diverging.
  • The number depends on how varied your customers are and how broad your question is, so a wildly mixed audience needs more conversations than a narrow one.
Open nngroup.com →

People also ask

What does 'jobs to be done' actually mean? People don't buy products, they 'hire' them to make progress in a specific situation, the famous milkshake was hired to make a boring commute beara... Beginner 2 resources → How is JTBD different from features, personas, or user needs? Personas describe who; JTBD describes the progress they're trying to make and the struggle that pushes them to switch. Features are your answer; th... Intermediate 2 resources → How do I actually uncover the job my customers are hiring my product for? Interview people who recently switched to or bought something in your space and reconstruct the timeline: what triggered the search, what they used... Intermediate 3 resources → Who are my real competitors once I think in jobs to be done? Anything the customer currently 'hires' to get the same job done, including a spreadsheet, a WhatsApp group, a competitor, or doing nothing at all.... Intermediate 3 resources → How do I turn a job to be done into product and messaging decisions? Write the job as a struggling-moment statement ('when I ___, I want to ___, so I can ___') and use it as the filter for what to build and how to pi... Advanced 2 resources → Customers say they want feature X, but is that the job or just a solution they've imagined? Almost always it's a solution they've imagined, and building it verbatim is how founders ship features nobody uses. The job hides one layer beneath... Intermediate 3 resources →