Product–market fit is felt before it is measured. These are the signals worth tracking from day one.
Founders often ask how they will know when they have product–market fit. The honest answer: you will feel the pull. But there are concrete signals you can track long before that moment arrives.
Retention beats acquisition
Growth that leaks out the bottom is not growth. Look at cohort retention: do users from three months ago still use the product today? A retention curve that flattens rather than dropping to zero is one of the strongest early signals you can show.
Ask the disappointment question
Survey active users with one question: how would you feel if you could no longer use this product? When roughly 40% or more answer "very disappointed", you are onto something. Read the reasons carefully — they tell you who your best customers are.
Watch for organic pull
Unprompted referrals, customers asking for features you planned for next year, and buyers who chase you for contracts are signs that the market is pulling the product from you rather than you pushing it.
Narrow before you widen
Most companies find fit with a specific segment first. It is better to have 100 users who love you than 10,000 who are lukewarm. Find the segment with the strongest signal and build for them relentlessly.
Product–market fit is not a single moment; it is a range you move through. Keep measuring, keep talking to customers, and let the data tell you when to pour fuel on the fire.