Effects of excluded volume interaction on the form factor of a block copolymer micelle model have been investigated by performing Monte Carlo simulations. The micelles are modeled as a corona of semi-flexible chains tethered to a spherical core. Simulated form factors are analyzed using the model proposed by Pedersen and Gerstenberg. A slightly modified model is presented, in which chains consists of a radially pointing rigid rod, onto which a Gaussian chain is attached. The straight section emulates chain stretching near the micelle core. Both models are fitted to the simulation data using two parameters, that describes the individual chains: the radius of gyration, and the average center-of-mass distance to the micelle core. Based on a comparison between parameters obtained from fits, and those obtained directly from the simulation, it is concluded that the models provide good estimates for the radius of gyration and the chain center-of-mass distance for a low surface coverage, while systematic deviations are observed for high surface coverage, where chains begin to overlap, and excluded volume interactions becomes significant.