A theoretical model of axisymmetric turbulent fountains in both homogeneous and stratified fluids is developed. The model quantifies the entrainment of ambient fluid into the initial fountain upflow, and the entrainment of fluid from both the upflow and environment into the subsequently formed downflow. Four different variations of the model are considered, comprising the two most reasonable formulations of the body forces acting on the ‘double’ structure and two formulations of the rate of entrainment between the flows. The four model variations are tested by comparing the predictions from each of them with experimental measurements of fountains in homogeneous and stratified fluids.