The power Plant in this study has 4 power generating units of 350 MW Capacity each. It is essential to optimise load distribution over four generating units in order to reduce the operational costs. A model has been developed in this study that takes into account a wide variety of operating conditions and calculates the optimum unit loads. The potential benefits that can be achieved from optimised unit loading over evenly loaded units are outlined. To correctly distribute loads across the units, the heat rates for the individual units has been determined and corrections have been made in heat rate calculation to allow for the variation in coal quality, air temperature, humidity and key operational factors such as condenser vacuum and steam pressure. The corrected heat rate is then used to calculate the load distribution across the four generating units for optimum performance which ensures the most cost effective means of producing power in existing plant. The method used to optimise heat consumption across the units has been discussed. Load distribution philosophy has been developed and the issues of integrating such a program into the control system have been discussed. The energy and monitory savings that can be achieved by using optimised unit loading in opposed to using even load distribution across the units have been determined. The results obtained indicate that a monetary savings of greater than $250 per hours can be achieved which equates to an annual savings of at least $1.04 million for the referenced power plant.