A wearable device is wearable on an appendage of a user and includes a force-sensitive display screen to generate force data when a force is applied to the force-sensitive display screen, a photoplethysmogram (PPG) sensor, and one or more processors. The PPG sensor is positioned below an external surface of the force-sensitive display screen and generates PPG sensor data when the force is applied to the force-sensitive display screen. The one or more processors are configured to: determine, from the PPG sensor data and the force data, a variation of PPG blood volume pulse amplitude with a variation in pressure applied to the appendage, and calculate an estimate of blood pressure of the appendage from the variation of PPG blood volume pulse amplitude with the variation in the pressure applied to the appendage.