Definition
Product-market fit is when a product meets a strong need of a specific market so well that customers keep using it, tell others and are disappointed at the thought of losing it.
Signs in the data
- Retention curves that flatten: a cohort keeps a steady share of users after the early drop.
- Organic growth: a rising share of sign-ups from word of mouth.
- Usage frequency: a group that uses the product as a habit.
A survey signal
Asking users how they'd feel if they could no longer use the product, and counting "very disappointed", is a widely used complement to the data.
Fit is specific
Fit is usually strong for one segment first. Break retention down by customer type and source to find it.