Dairy farm businesses continue to face many challenges and in future years will have to make decisions that are critical in terms of the farming systems they choose to operate alongside giving consideration to adapting systems in order to maintain profitable and sustainable businesses going forward. In this context, there is a need to develop a model to explore a range of systems from both an industry and policy perspective. Farmers will require advice and guidance in relation to which systems or adaptations to systems will be best under a range of factors. This study developed a whole farm dairy model for Northern Ireland. This paper provides an overview of the model developed and an application looking at three different dairy systems and the effect of price changes on them.