Current-user retention rate (CURR)

• Metric

  Clients retained at 12 months

  share of clients still booking after a year

  Share of a first-booking cohort that books again within the 12 months after it. The Stay health metric for service businesses.

• Metric

  Cadence-matched cohort retention

  cohort retention at the natural cadence

  Share of a sign-up or activation cohort that does the value event in a later bracket matched to the product's natural cadence (for example week 4 or week 8). Read by segment for curve shape and across cohorts for stacking.

• Metric

  DAU/MAU stickiness

  daily share of monthly actives

  Average daily actives divided by monthly actives (value event, not logins). Meaningful mainly for daily social and messaging products; weekly products use WAU/MAU. Episodic products can be great businesses with low ratios.

• MetricARobustEvidence grade A. Robust evidence: replicated, peer-reviewed research.

  Email unsubscribes per campaign

  email opt-outs per send

  Unsubscribes divided by emails delivered, per campaign. A guardrail for email triggers and win-back flows; lower is better.

• Metric

  Habitual-user rate

  share at the devoted cadence

  Share of activated users who meet the route's devoted cadence in the read week (week 8 by default). Compared with a 5% bar that is Hooked's rule of thumb, not a scientific cut-off, and read on the habit horizon.

• Metric

  Hook cycle time

  time from investment to the next visit

  Median time from an investment that loads a trigger, to that trigger's delivery, to the session it starts. Shorter cycles mean more loops and faster habit formation.

Sources

• Meaningful metrics: the Duolingo growth model · Duolingo Blog (Erin Gustafson), 2023

  APrimaryBenchmark confidence A. A primary source for the benchmark.

Book content is paraphrased, never quoted at length. Last verified October 24, 2026.