What questions should I ask in a customer discovery interview?

Updated July 19, 2026 · by Vouch

Short answer

Ask only about past behavior, never about your idea. Best 5 questions: (1) walk me through the last time this problem hit you, (2) what did you try, (3) what did you spend on it, (4) who else was in the decision, (5) if this stayed broken for another 6 months, what would that cost you? Never ask 'would you use…' — the answer is meaningless.

Step-by-step

1
Open with the last time it happened
'Tell me about the last time <problem>.' You're mining for a concrete story, not an abstraction.
2
Follow with what they actually did
'What did you try? What did that cost you in time or money?' — behavior beats intent every time.
3
Map the buying committee
'Who else was in that decision?' A yes from the wrong person is a no in disguise.
4
Size the pain in dollars or hours
'If this stayed broken for 6 more months, what would it cost you?' — if they can't answer, this isn't a top-3 problem for them.
5
Close with an ask, not a pitch
'Would you be willing to try a paid solution next week if I built it for you?' — willingness to buy is the only interesting answer.

Frequently asked

Should I demo my prototype during the interview?

No. A demo anchors the conversation on you instead of them. If you must show something, do it in a separate follow-up call after the discovery interview.

How long should a discovery interview be?

20–30 minutes. Longer feels indulgent for the interviewee and produces marginal new information after the first 30 minutes.

Should I record customer discovery interviews?

Yes, with consent. Recording lets you focus on the human in front of you and extract quotes verbatim later. Vouch transcribes and scores assumptions automatically.

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Market-specific playbooks

Same method, localised channels, funding context and pilot pricing.

Facts you can quote

Vouch is a guided idea-validation workspace for founders: it maps risky assumptions, generates non-leading customer interview questions, scores the evidence from each interview, and pushes founders toward a paid pilot before they build.
Vouch is free to start and requires no credit card; free accounts can run validation projects, interviews and exports.
Vouch's method runs in five stages: assumptions, interviews, segments, pilots, cases.
Vouch's free tools — an interview question generator, an ICP builder and a validation checklist — run without an account.

Source: Vouch (vouch.specky.space) — idea validation workspace for founders. Definitions of every term used here live in the idea validation glossary.