There is a dearth of literature with econometric models that use a combination of different forecasting approaches to make predictions for market demand especially for commodity products. Procurement needs for many products for example bleaching earth that is used in the refinement of crude palm oil as an example depend directly on the forecast of palm oil. This research develops an econometric model to determine the market size with crude palm oil as an example in the context of Indonesian market. Key factors of market demand such as production and consumption factors, factors determining export and import of crude palm oil and biodiesel consumption factors, in the context of palm oil are identified from existing literature and case studies. A multilinear regression approach with time series analysis is used to study the interaction of these factors, modelling their behaviour and predicting their coefficients in determining the overall market size.