PMF Survey (Sean Ellis 40% Rule)
Use it when you need a quick, data-driven check if your product truly resonates with users.
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What is it?
The PMF Survey with Sean Ellis's 40% Rule is a razor-sharp, single-question benchmark that tells you if you've hit product-market fit.
You fire off a survey to your most active users asking, “How would you feel if you could no longer use [Your Product]?” and classify responses into ‘very disappointed,' ‘somewhat disappointed,' or ‘not disappointed.' Then you calculate the percentage of ‘very disappointed' answers: if it's 40% or higher, you've likely nailed PMF. This simple user feedback loop solves the core startup problem of knowing, beyond gut feel, whether your product solves a real market pain.
It breaks PMF down into a clear metric, so you can track improvements over time, validate pivots, and align your roadmap around features that drive true retention.
Why it matters?
PMF Survey gives you a hard number instead of wishful thinking, so you can prove that your product not only attracts users but becomes indispensable. Hitting higher ‘very disappointed' percentages correlates directly with better retention, higher referrals, and faster sustainable growth.
How it works
Growth co-pilot turns your toughest product questions into clear, data-backed recommendations you can act on immediately.
1
Define your sample
Pick at least 40 active users who've engaged with your core feature in the last 30 days to ensure statistical relevance.
2
Send the survey
Ask the key question, “How would you feel if you could no longer use [Product]?”, plus optional follow-ups on usage frequency and referral intent.
3
Categorize responses
Tally ‘very disappointed,' ‘somewhat disappointed,' and ‘not disappointed' answers in your survey tool or spreadsheet.
4
Calculate your PMF score
Divide the ‘very disappointed' count by total responses, multiply by 100, and compare against the 40% rule.
5
Interpret and iterate
Over 40% signals strong PMF; 30–40% is cautionary; under 30% means you need to refine your core value. Plan experiments based on where you fell short.
6
Segment deeper
Break your PMF score out by user persona, acquisition channel, or feature usage to uncover pockets of true product enthusiasm.
Frequently asked questions
Growth co-pilot turns your toughest product questions into clear, data-backed recommendations you can act on immediately.
You've nailed your PMF score, now don't stop there. Run the CrackGrowth diagnostic to uncover the funnel leaks holding back your next growth spurt and prioritize the experiments that push your score skyward.