Retention Curve

A retention curve plots the percentage of a cohort still active N days (or weeks) after they signed up, tracing how usage decays over time. Its shape tells you more than any single number: a curve that keeps sloping toward zero means you have a leaky bucket and no product-market fit, while one that *flattens* into a horizontal plateau means a stable core of users found lasting value — the classic sign builders look for. The height of that plateau is roughly your ceiling for organic growth. Two definitions matter: N-day retention (active on exactly day N, strict) versus unbounded/range retention (active anytime in a window, more forgiving) — pick one and label it, because they produce very different-looking curves. Practical note: measure retention on your genuine core action (the thing that delivers value), not just logins, and always segment by cohort and acquisition source, since a blended curve hides that one channel is churning while another sticks. Flattening beats a high day-one number.