Recovery is highly personalized to each user. As such, Recovery goes through a calibration period during which WHOOP learns about you and an educated baseline is set.
The first time you record a Sleep on WHOOP, your data is compared against typical Recovery metrics (like HRV and Resting Heart Rate) based on your age, gender, and fitness level. While the majority of your data is compared to these defaults, Recovery is treated as “calibrating”. As more of your personal data is measured, your Recovery calibrates and your personalized baseline is used to generate your Recoveries. Your Recovery is considered to be calibrated to your own physiology after 4 Recoveries.