How do I know I have PMF?

Key signs: 40%+ 'very disappointed,' a flattening retention curve, and growing word-of-mouth.

Should I avoid marketing before PMF?

Small experiments are fine, but save big ad budgets until PMF is confirmed.

Product-market fit

💼 Business By CampusDown Wiki Editorial Team Last updated October 26, 2026

Product-market fit (PMF) is the point where a product solves a real problem in a large enough market that customers seek it out, keep using it, and recommend it to others.

Contents

1. History
2. How to measure it
3. Finding it, and cautions
4. FAQ
5. References

History

Andy Rachleff, a co-founder of Benchmark Capital, concluded that the market is the biggest reason startups fail and developed the idea of product-market fit. In his 2007 essay "The only thing that matters," Netscape co-founder Marc Andreessen defined PMF as "being in a good market with a product that can satisfy that market," and the phrase became Silicon Valley vocabulary. With PMF, he wrote, customers buy as fast as you can make the product. Without it, nothing quite works. CB Insights has likewise found "no market need" to be the top reason startups fail.

How to measure it

In 2009 Sean Ellis proposed asking users, "How would you feel if you could no longer use this product?" If at least 40% answer "very disappointed," you've likely reached PMF. Email app Superhuman started at 22%, used the survey to study its core users, and improved the product until it hit 58%. Behaviorally, check whether your retention curve, the share of users still active over time, flattens instead of sliding to zero. Rising organic and referral growth, a strong Net Promoter Score, and low churn are further signs.

Finding it, and cautions

Founders usually find PMF the lean startup way: launch an MVP, watch customer behavior, and pivot the product or target market as needed. Slack began as an internal chat tool at a game company. Instagram grew out of Burbn, a check-in app, by keeping only its photo feature. Pouring ad money into growth before PMF is like filling a leaky bucket. And PMF isn't permanent; it can slip away when markets change.

FAQ

How do I know I have PMF?: Key signs: 40%+ 'very disappointed,' a flattening retention curve, and growing word-of-mouth.
Should I avoid marketing before PMF?: Small experiments are fine, but save big ad budgets until PMF is confirmed.

Sources reviewed: 2026-10-26

References

Andreessen, M. (2007). The only thing that matters. pmarchive.com.
Rachleff, A. (2007). Benchmark Capital; cited in Andreessen (2007).
Ellis, S. (2009). Using product/market fit to drive sustainable growth. Startup Marketing blog.

Reports and materials that use this theory (Korean)

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This article was last updated on October 26, 2026. It is based on widely recognized original works and textbooks; when citing it in a paper, please check the original sources listed in the references.