Product-Market Fit Score
How disappointed users would be without your product. The earliest reliable signal of PMF.
What it measures
A survey-based leading indicator of product-market fit. Ask users: "How would you feel if you could no longer use [product]?" Options: Very disappointed, Somewhat disappointed, Not disappointed. The percentage answering "Very disappointed" predicts growth potential.
Calculation Variants
- The Sean Ellis Test
- Send to all active users. The original 40% threshold metric.
- The Superhuman Method
- Send only to users who have experienced the core value proposition (e.g., sent 5+ emails). Excludes noise from un-activated users.
What to watch
- Above 40%: Strong product-market fit indicator — this is Sean Ellis’s 40% threshold. Slack scored 51% on this survey when validating PMF. Companies crossing the threshold typically see organic growth accelerate.
- Below 40%: Keep iterating. Your product solves a problem but isn't yet a must-have. Focus on understanding what "very disappointed" users love and double down on that.
In practice
A productivity tool launched with 28% PMF score. The team analyzed the "very disappointed" segment and found they all used one specific feature: automated time blocking. They rebuilt the entire product around that feature, and PMF score rose to 47%. The pivot was informed by users who already loved them, not average users.
Illustrative scenario — a representative composite, not a specific company.
Related: NPS — loyalty measure.; Activation Rate — PMF depends on users experiencing core value.