Allocation of contention slots (CS) is an open area for research in WiMAX networks. This is because the wimax standard does not specify the amount of bandwidth to be used in the uplink for contention.In this article s model for evaluating the effect of CS allocation on access delay has been proposed using normalized throughput and number of subscriber stations to evaluate how the number of contention slots affect access delay. It has been clearly shown that increase in number of contention slots has an effect on access delay at the expense of system throughput, therefore the number of CS used for granting bandwidth request affects the QoS of the network. In the analysis, it has been shown that increase of CS more than 2000CS has no meaningful influence on access delay. This was validated by simulation using Matlab 2012. Network operators could use these values in the planning of WiMAX networks.