GlossaryGrowth & analytics
What is product-market fit?
Also called: PMF, product/market fit, Sean Ellis test
Definition
Product-market fit (PMF) is the point where a product satisfies a strong market demand: customers use it, keep using it, pay for it and recommend it, with growth pulling the company rather than being pushed.
Product-market fit (PMF), explained
Marc Andreessen's 2007 essay "The only thing that matters" gave the phrase its common definition: product/market fit means being in a good market with a product that can satisfy that market. He describes the difference vividly. Without fit, customers aren't getting value, word of mouth isn't spreading, usage isn't growing fast, and sales cycles drag. With it, in his words, customers are buying the product just as fast as you can make it.
The best-known way to measure it comes from Sean Ellis. His survey asks users how they would feel if they could no longer use the product: very disappointed, somewhat disappointed, or not disappointed. As First Round Review recounts in its piece on how Superhuman measured PMF, Ellis found after benchmarking nearly a hundred startups that companies with strong traction almost always had more than 40% of users answer "very disappointed", while struggling ones almost always had less.
The survey is useful because it's cheap and specific, but ask the right people: users who have actually used the product recently, not everyone who ever signed up. Superhuman's approach went further, segmenting the "very disappointed" group to understand who they were and what they loved, then building for more people like them.
Other signals help triangulate: retention curves that flatten, organic word-of-mouth sign-ups, customers who complain loudly when something breaks, and sales that get easier without extra effort.
PMF also matters for marketing order. Pouring launches, SEO and ads into a product without fit mostly brings people who leave. Once retention and the survey say you're close, those channels compound.
Why it matters for founders
Nearly every growth tactic works better after product-market fit and worse before it. Knowing where you stand tells you whether to spend the next month on product or on distribution.
Example
A startup surveys 120 active users: 28% would be very disappointed without the product. Segmenting shows agencies answer 52%. It narrows its focus to agencies, and the overall score rises above 40% two quarters later.
Common mistakes
- Surveying every sign-up instead of recent active users.
- Scaling acquisition before retention flattens.
- Treating PMF as a one-time milestone rather than something to keep.
Sources
- Marc Andreessen: The only thing that matters (2007)
- First Round Review: How Superhuman built an engine to find product/market fit
Checked
Related terms
- RetentionRetention is the share of users or customers who keep using or paying for your product over time, usually measured for a cohort that started in the same period. It's the clearest signal that a product delivers lasting value.
- Minimum viable product (MVP)A minimum viable product (MVP) is the version of a new product that lets a team learn the most about its customers with the least effort. Its purpose is validated learning, not simply shipping something small.
- Ideal customer profile (ICP)An ideal customer profile (ICP) is a description of the type of customer, usually a company or person with specific traits, who gets the most value from your product and is most valuable to your business in return.
- North star metricA north star metric is the single metric that best captures the core value customers get from your product, used to align a team's work. It should rise when customers get more value, not just when revenue or traffic does.