What is Product-Market Fit?

Product-market fit (PMF) means being in a good market with a product that can satisfy that market. Marc Andreessen coined the term and says 'you can always feel when product-market fit is happening — customers are buying as fast as you can make it.'

How to measure PMF:

1. Sean Ellis Test — Ask users 'How would you feel if you could no longer use this product?' If 40%+ say 'Very disappointed,' you have PMF.

2. Retention curve — If your monthly retention stabilizes (doesn't drop to zero), you have PMF.

3. NPS > 40 — A Net Promoter Score above 40 is a strong PMF signal.

4. Organic growth — If 50%+ of new users come from word-of-mouth or organic channels.

The truth about PMF: It's not a binary switch — it's a spectrum. You can have PMF in one segment but not others. Start narrow, find PMF in a niche, then expand.

Pre-PMF checklist:
•Don't spend on growth marketing
•Don't over-hire
•Spend 80% of your time talking to users and iterating
•Ship weekly, not quarterly