Companies and their factories face constant change in today's world. Cost-intensive factory planning projects are being carried out in shorter intervals due to the increasing dynamism of the production environment. The related investments have a substantial impact on the liquidity of companies. Shorter production life cycles and changing consumer behaviour also require an adapted and more sustainable factory planning and cost estimation. However, especially in an early planning phase, available data and information are often uncertain and inaccurate. This effects in particular the outcome of the central dimensioning variables (operating resources, employees and area) for the planned factories. Incorrect dimensioning of these variables and thus of the associated costs can lead to substantial misinvestments. A holistic approach to obtain a reliable cost estimation of the factory project at an early stage is not yet available. This article therefore presents the development of a comprehensive procedure model for dimensioning and investment cost calculation in an early factory planning phase. For this purpose, relevant information and planning tasks with regard to dimensioning and cost estimation have to be identified first. Determined output values of the subsequent resource dimensioning represent the input values for the cost calculation. With the identification of surcharge factors, cost rates and calculation methods, the dimensioning variables, in particular the production area as the basis for the planned factory, can be estimated in terms of costs at an early stage.