Drops residing on cylindrical surfaces are widely encountered in nature and in applications. A variable-radius cap model is established here using three parameters to approximately describe their shapes when the effect of gravity is insignificant. The morphology of a drop on cylinders with different radii and wetting properties has been simulated using Surface Evolver. The characteristic parameters of drop morphology, the maximum radius, minimum radius and height, are used to validate the model. It indicates that the model is accurate for Young's contact angle over 20 and for radius of cylinder a few times greater than that of the drop. The transition condition of drops from a clam shell to barrel conformation can be obtained based on the theoretical model. The ability to rapidly obtain the drop morphologies presents vistas in conducting improved three dimensional simulations of heat and mass transfer as the drop evaporates from fibers and cylinders. (C) 2015 Elsevier Ltd. All rights reserved.