AbstractCapital cost estimation for chemical plant. During the preliminary stages of an investment project (before approval), several decisions have to be made on whether or not it should be pursued. Therefore cost estimates are required with stepwise reduction in uncertainty. However, the attainable accuracy of a cost estimate is a function of progress in engineering the entire project. Thus, each step in cost estimation entails a higher degree of planning and demands methods that satisfy the accuracy demanded and correspond to the progress made in engineering. A comprehensive estimation system has been developed from these interrelations, and the respective procedures are described. This paper considers known fundamentals and the authors' own developments.