Your product has users. Customers are paying. Growth is happening. But something feels off. Churn is high. Sales cycles are long. Most prospects say "interesting, but not now." You're growing, but it's hard.
The question haunting every founder and product marketer: Do we actually have product-market fit, or are we just fooling ourselves?
Sean Ellis, who coined the term "growth hacking," created a simple test to answer this question quantitatively. The Sean Ellis Test cuts through vanity metrics and subjective feelings to reveal whether you've built something people truly need.
What Is Product-Market Fit?
Product-market fit means you've built a product that satisfies a strong market demand. Marc Andreessen famously described it as "being in a good market with a product that can satisfy that market."
When you have it, you know. Customer acquisition is easier. Retention is higher. Word-of-mouth drives organic growth. Customers describe your product as essential, not nice-to-have.
When you don't have it, growth is a grind. Every customer requires heavy sales effort. Churn is high because customers don't see enough value to stay. Expansion is difficult because customers won't commit more resources to something that's not critical.
Most products die before achieving product-market fit. They have customers, but not enough customers who care deeply enough to sustain a business.
The Sean Ellis Test
Sean Ellis discovered a pattern while working with high-growth startups. Companies that achieved sustainable growth had one thing in common: at least 40% of their users said they would be "very disappointed" if the product went away.
This became the Sean Ellis Test:
Survey your active users with one question: "How would you feel if you could no longer use [product]?"
Provide three answer options:
- Very disappointed
- Somewhat disappointed
- Not disappointed
Calculate the percentage who answer "very disappointed."
If 40% or more say "very disappointed," you likely have product-market fit. If fewer than 40% feel that way, you probably don't—regardless of other metrics.
This threshold matters because products that clear 40% demonstrate they're solving critical problems for a significant portion of users. These users find the product essential, not just useful.
How to Run the Survey Properly
The test seems simple, but implementation matters. Common mistakes invalidate results.
Survey the right users: Only survey people who've used your product recently and meaningfully. If someone signed up six months ago and never came back, their opinion doesn't matter. Survey users who've been active in the past two weeks and completed key workflows.
Reach sufficient sample size: You need at least 40 responses, ideally 100+, to trust the results. Ten responses from your friendliest customers don't count.
Ask early enough to act: Run this survey after users have experienced your core value proposition but before you've invested heavily in scaling. For most products, that's 2-4 weeks after signup for users who've completed onboarding.
Include follow-up questions: After the main question, ask:
- "What is the primary benefit you receive from [product]?"
- "What type of people do you think would most benefit from [product]?"
- "How can we improve [product] for you?"
These qualitative responses reveal what's working and what needs improvement.
Segment your results: Break down responses by customer type, use case, or acquisition channel. You might find 60% of customers from one segment would be "very disappointed" while only 20% from another segment feel that way. This reveals where you have fit and where you don't.
What Different Scores Mean
The 40% threshold isn't a binary pass/fail. Different ranges suggest different strategic actions.
Below 25%: You don't have product-market fit. Most users don't find your product essential. Before scaling marketing or hiring more sales reps, figure out why users don't care deeply.
Common reasons: you're solving a nice-to-have problem, not a must-have; your product doesn't solve the problem well enough; you're targeting the wrong customer segment; you have fundamental product issues.
Action: Talk to users. Understand why they're not disappointed. Either pivot to serve a different need, improve product capabilities significantly, or find a different customer segment with more urgent needs.
25-40%: You're close but not there yet. A meaningful segment finds value, but not enough. You have something worth building on.
Action: Identify the users who would be "very disappointed." What do they have in common? Double down on that segment. Build more features they need. Market specifically to people like them. Ignore users who wouldn't care if you disappeared.
40-50%: You have product-market fit with your current segment. You can grow, but focus on retention and deepening value for current users before massive expansion.
Action: Understand what drives the "very disappointed" segment's attachment. Make that value even stronger. Expand features that deepen moats. Improve onboarding to get more users to experience core value faster.
50%+: You have strong product-market fit. Users are deeply attached. You're solving critical problems well.
Action: Scale go-to-market. Double down on customer acquisition. The product is ready; focus on distribution, sales enablement, and capturing market share.
How Product Marketers Use This Framework
Product-market fit fundamentally affects product marketing strategy.
Positioning: If you don't have PMF, your positioning won't matter. No amount of clever messaging fixes a product people don't need. If you have PMF, your positioning should emphasize the critical problem you solve, using language from the "primary benefit" responses.
Segmentation: Analyze which customer segments score highest. These become your ICP. Market exclusively to segments that show PMF signals. Ignore segments below 40% until you've dominated the high-fit segments.
Messaging: The "primary benefit" responses from "very disappointed" users become your core messaging. These users articulate value in their own words—use that language in your marketing.
Product roadmap input: Features should strengthen reasons users would be "very disappointed" to lose you. If users value speed, prioritize performance. If they value collaboration features, build more team capabilities.
Sales enablement: Train sales to identify prospects who look like your "very disappointed" users. Qualification should screen for characteristics that correlate with high fit.
Common Mistakes with the Test
Surveying too few people: Results from 10 friendly customers aren't statistically meaningful. You need enough responses to overcome selection bias.
Surveying the wrong people: Surveying everyone in your database including inactive users dilutes results. Survey recent, active users who've experienced your value proposition.
Ignoring segmentation: Overall score might be 35%, but one segment scores 65%. That's buried treasure. Segment your data to find pockets of strong fit.
Running it once and forgetting: PMF isn't binary or permanent. Run this quarterly. As you change product, positioning, or target market, fit changes. Monitor it continuously.
Treating 39% as failure: If you score 38%, you're close. Identify the gap. Often you need better onboarding, not a different product. Users who experience core value fully usually score higher.
Ignoring qualitative feedback: The quantitative score matters, but the "why" matters more. Read every single comment. Look for patterns in what drives satisfaction and disappointment.
Beyond the Initial Test
Once you've achieved 40%+ on the Sean Ellis Test, continue measuring related metrics that indicate PMF strength.
Net Promoter Score (NPS): How likely are users to recommend your product? NPS correlates with PMF but isn't the same. You can have good NPS with weak PMF if users like your product but don't find it essential.
Retention cohorts: What percentage of new users are still active after 30, 60, 90 days? Strong PMF shows increasing retention as users discover more value over time.
Organic growth rate: How much growth comes from word-of-mouth, referrals, and viral mechanics vs. paid acquisition? Strong PMF drives organic growth.
Customer Acquisition Cost (CAC) payback: How long to recover CAC? With strong PMF, customers buy faster and stay longer, improving CAC payback.
Usage frequency: Are users engaging daily, weekly, or monthly? Increasing usage frequency often indicates deepening PMF as users find more use cases.
When You Don't Have Product-Market Fit
If your score is below 40%, don't panic. Most products start here. The test reveals reality; it doesn't create failure.
Your options:
Pivot to a different segment: Maybe your product has PMF with a segment you're not targeting. Enterprise might love what SMB finds lukewarm. Or vice versa.
Improve the product: Perhaps the value proposition is right but execution is weak. Better UX, more features, or improved performance might move users from "somewhat disappointed" to "very disappointed."
Solve a different problem: Maybe you're solving the wrong problem. Customer interviews might reveal a more urgent pain point you could address.
Narrow the focus: Sometimes trying to be everything to everyone creates mediocre fit with many segments. Picking one segment and serving them deeply can create strong fit.
The worst response is ignoring the data and scaling anyway. That path leads to high CAC, poor retention, and eventually running out of money.
When to Use the Sean Ellis Test
Use this test when:
- You're deciding whether to scale go-to-market
- Growth has stalled and you don't know why
- You're considering major product changes
- You need to validate that recent improvements worked
- You're reporting PMF status to board or investors
Don't use it when:
- You have fewer than 50 active users
- Your product just launched and users haven't experienced core value
- You're in rapid iteration and changing fundamentals weekly
Product-market fit takes time to assess. Give users time to integrate your product into workflows and experience full value before testing.
The Sean Ellis Test won't tell you how to achieve product-market fit. But it will tell you honestly whether you have it. And that honesty—knowing where you really stand—is the first step to building something people truly need.