The author's describe the practice of cost planning at several RIBA Plan of Work design stages. They embark on a detailed description of cost-planning practice. The author's starts the cost-planning process with the predesign stage, which they have termed the briefing stage for simplicity, and this stage consists of two Plan of Work stages: Strategic Definition and Preparation and Briefing. The cost-planning result of the strategic definition and briefing stage is a global cost figure that may be considered to be the first estimate. The preparation and agreement of the strategic brief with the client at this initial stage eventually leads to the preparation of an initial project brief. The author's concentrate on defining and describing the various types and methods of preparing approximate estimates aimed at setting the budget of the capital cost, which forms the basis of the Feasibility Studies that are an essential part of the decision making.