The quality of solution obtained using FA depends upon number of iterations and population size. Hence first step to solve loadability problem is to select a suitable population size and number of iterations for 30 bus, 118 bus and 300 bus test systems. As in AI based techniques it is difficult to predict a single value obtained as a best or worst solution. Therefore in this paper, 50 trials are run for each population size for given number of iterations for all test cases.