In a method for determining force applied to an ultrasonic sensor, ultrasonic signals are emitted from an ultrasonic sensor. A plurality of reflected ultrasonic signals from a finger interacting with the ultrasonic sensor is captured. A first data based at least in part on a first reflected ultrasonic signal of the plurality of reflected ultrasonic signals is compared with a second data based at least in part on a second reflected ultrasonic signal of the plurality of reflected ultrasonic signals. A deformation of the finger during interaction with the ultrasonic sensor is determined based on differences between the first data based at least in part on the first reflected ultrasonic signal and the second data based at least in part on the second reflected ultrasonic signal. A force applied by the finger to the ultrasonic sensor is determined based at least in part on the deformation.