Definition
D7 (Day 7) Retention measures the proportion of a signup cohort that returns to use the product exactly 7 days after their first session. It is the most widely tracked early retention metric because it captures whether users found enough value in their first experience to form a weekly habit. D7 retention is a critical inflection point: users who survive the first week are dramatically more likely to become long-term users.
Formula
How to measure
For each signup cohort (e.g., all users who signed up on March 1), check how many had at least one active session on Day 7. Express as a percentage of the original cohort size. Use unbounded retention (any activity on or after Day 7) or bounded retention (activity specifically on Day 7) — be consistent.
Industry benchmarks
Consumer apps: 20–35% is typical; 40%+ is excellent. SaaS B2B products: 35–50% is healthy. Social/messaging apps: 40–60%. Below 15% for any category signals a fundamental value delivery problem.