Techniques are described for determining height, weight, or other characteristics of a user based on processed sensor data. The sensor data may include data collected by sensors on the user's computing device or other computing devices, or data collected by stationary, external sensors. Different types of sensor data may be processed to estimate at least one physical characteristic of the user, such as the user's height, weight, apparel size, age, and so forth. The estimated characteristics may be employed to perform actions based on the user's identity or category, to customize content delivery for the user, or for other purposes.