Formula
Trial users who become paying customers / Total trial signups x 100
How to measure
Track each trial cohort by signup date and measure what percentage convert to a paid plan within or shortly after the trial window.
Why track it
This is the core efficiency metric of a trial-based funnel, and small improvements here compound directly into revenue without any new acquisition spend.
Example
Of 600 users starting a 14-day trial, 90 convert to paid, a 15% trial-to-paid conversion rate.