The Never Ending Road To Product Market Fit
Brian Balfour argues that product-market fit isn't a single moment but a series of tests that get harder and more convincing: surveys, engagement data, retention curves, and finally the combination of growth, retention and usage. Where you are on that path tells you when to start investing in growth.
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We link to the original and never republish it. All credit to Brian Balfour.
Key takeaways
- Treat the 'how would you feel if you could no longer use this' survey (40% 'very disappointed') as an early signal, not proof.
- Measure actions tied to your product's core purpose, not passive views.
- Look for a retention curve that flattens; without retention, faster growth means little.
- Fit is near-certain when growth, retention and meaningful usage show up together.
- Keep checking fit as you grow and enter new segments; incumbents often lose it.
Who it's for
Founders trying to judge honestly whether they have product-market fit before spending on growth.
Why it's worth your time
Written in 2013, but the checkpoints still hold and remain one of the clearest ways to think about fit.
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