Despite the widespread applications of electrospun fibers, there is still no accurate method to measure the thickness or porosity of thin electrospun mats. The current study is devised to develop a modeling approach toward solving this problem by simulating the 3-D structure of nanofiber mats. The uniqueness of our algorithm is in its ability to capture how the fibers conform to the geometry of the surface on which they deposit. This feature is important for predicting how the thickness of a nanofiber mat grows as fibers continue to deposit on the collector. Our algorithm is implemented in a C++ computer program, and is used to study the effects of fiber rigidity, fiber diameter(s), and fiber orientation on the thickness and porosity of electrospun mats. Contrary to the common belief, it was shown that reducing fiber diameter, while maintaining the total weight of the material constant, does not necessarily lead to an increase in the thickness and porosity of the resulting mat. The thickness and porosity of electrospun mats were shown to depend on fibers' tendency to bend at the fiber-fiber crossovers, which may vary depending on the properties of the fibers and the electrospinning process conditions. (C) 2016 Elsevier Ltd. All rights reserved.