Essay · Short read (tweetstorm plus commentary)

Magic metrics indicating product/market fit (cohort curves that flatten, and the power user smile)

Andrew Chen · andrewchen.com Free Intermediate

The real signal of product market fit is not a headline retention number, it is whether your cohort retention curve stops falling and flattens into a stable base of users who keep coming back. Andrew Chen is the canonical voice on this mental model, and he pairs the flattening curve with the power user smile so you can see where your sticky core actually lives. Read it as the frame for judging your own numbers, not as a pass/fail line.

  • A retention curve that flattens (instead of trending to zero) is the honest sign that some users are genuinely hooked.
  • The power user smile shows a concentrated core of engaged users that you can grow out from, so look at the shape, not just the average.
  • These are directional signals of product market fit, useful as a starting point rather than a strict benchmark to clear.
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The question it answers

  1. What retention benchmark should I actually aim for at pre-seed, and how do I know if my numbers are bad?

Read with it

  1. Once you know your curve should flatten, the next question is where it should flatten, and this piece answers it with concrete... Lenny's Newsletter Article · ~10 min read What is good retention? Lenny Rachitsky
  2. Benchmarks only matter once you can plot your own cohorts and see whether your curve is flattening, and Amplitude's Retention... Amplitude Docs Tool · Reference documentation plus free product Amplitude Retention Analysis (chart documentation) Amplitude
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