Tube bending is a widely used manufacturing process in the aerospace, automotive, and various other industries. During tube bending, considerable in-plane distortion and thickness variation occurs. Additional loadings such as axial force and internal pressure can be used to achieve better shape control. Based on plasticity theories, analytical models are developed to predict cross-sectional distortion and thickness change of tubes under various loading conditions. The model predictions are in good agreement with finite element simulations and published experimental results. The models can be used to evaluate tooling and process design in tube bending.