PMF survey is a lightweight research method—often called the Sean Ellis test—that measures product-market fit by asking users how disappointed they would be if they could no longer use the product.

How it works

Teams survey recent, active users—not churned accounts or casual trialists—with a core question: “How would you feel if you could no longer use [product]?” Response buckets typically include very disappointed, somewhat disappointed, and not disappointed. Practitioners often treat roughly 40% or more “very disappointed” among your best-fit users as a strong PMF signal, though context and segment matter.

Follow-up questions ask what type of user benefits most and what alternative they would use. That qualitative data sharpens ICP and roadmap priorities before paid acquisition scales.

Why it matters

• Founders: PMF surveys cheaply validate whether you are building for a must-have audience—not a nice-to-have novelty.
• Investors: A reported PMF score without sample definition (who was surveyed, when, and cohort size) carries little weight in diligence.

Common mistake

Surveying everyone including inactive signups, then celebrating a weak headline number. PMF measurement should target users who experienced core value recently.

Related ideas

See pivot, retention, and NPS style customer research.