Systems and methods are disclosed for determining individual-specific blood flow characteristics. One method includes acquiring, for each of a plurality of individuals, individual-specific anatomic data and blood flow characteristics of at least part of the individuals vascular system executing a machine learning algorithm on the individual-specific anatomic data and blood flow characteristics for each of the plurality of individuals relating, based on the executed machine learning algorithm, each individuals individual-specific anatomic data to functional estimates of blood flow characteristics acquiring, for an individual and individual-specific anatomic data of at least part of the individuals vascular system and for at least one point in the individuals individual-specific anatomic data, determining a blood flow characteristic of the individual, using relations from the step of relating individual-specific anatomic data to functional estimates of blood flow characteristics.
