Definition
Feature adoption rate is the share of active users who used a feature at least once in a period. It shows which features people find, and helps decide what to improve, promote or remove.
Formula
Feature adoption rate = users who used the feature ÷ active users × 100, in the same period.
Example
Of 2,000 weekly active users, 340 exported a report: adoption of 17%.
Beyond adoption
Adoption says how many tried it; frequency says whether they rely on it. Look at both, and at whether adopters retain better. See feature creep.
How to measure it
Give the feature its own event, with a user ID, and chart unique users of that event against active users.