1. A computer-implemented method, comprising: accessing, by a computer system, a three dimensional (3D) image of at least a portion of a finger of a hand of a user, the 3D image captured by a 3D imaging device; accessing, by the computer system, calibration information associated with the 3D image, the calibration information comprising a distance of the at least a portion of the finger from the 3D imaging device; generating, by the computer system, depth map information for the at least a portion of the finger from the 3D image; determining by the computer system, a dimension of the finger based at least in part on the depth map information and the calibration information, wherein the dimension comprises a circumference; updating, by the computer system, the determined dimensions of the finger based at least in part on a difference between the dimension of the finger and average dimension information derived from a plurality of users exceeding a threshold amount; identifying, by the computer system, a ring size for the finger based at least in part on the updated dimension of the finger; and generating, by the computer system, instructions to communicate the ring size to the user.