AbstractA model is presented that simulates on a microcomputer the fiber distribution in a planar arrangement applicable to thin sheets of composites. Although it does not take into account spatial fiber interference, the software allows one to investigate a number of important design parameters. The inputs used in the simulation are: thickness of the composite sheet, diameter and volume fraction of fibers along with fiber length, and angular position which can be specified in a number of ways. The program utilizes the internal random function to depict each fiber, as it is generated, in a “simulation window” of the monitor while the mathematics of the system are being done simultaneously within the smaller “valid window”. The procedure prescribes that the center of gravity of all fibers be uniformly distributed over the simulation window area. For that reason and because the 2D model is extended to simulate a three‐dimensional sheet, results will represent the ideal configuration or upper bonds of a corresponding practical case. Graphical representations and statistics are thus produced to quantify the geometric pattern of the system. One use of the model is, for instance, to see how the geometric patterns and their associated statistical parameters compare at a given volume fraction when the fiber length is fixed or when fiber length can be modeled as a normal, a uniform, or another specific dis