This paper sets out the basis to establish key performance indicators (KPIs) in manufacturing companies. Their significance and how they can be used to make improvements. KPIs have been chosen in order to deal with the possibility of improving the utilization of a process manufacturing plant. The objective is to present a new methodology for KPIs. Also methodologies on manufacturing performance measures taken from the literature are used for the solution of improving the utilization. They are discussed on the basis of a manufacturing experience. In this paper, a presentation of these methodologies, a critical evaluation and short examples of applying them are included. The main conclusion of this paper is that the KPIs can be used quantitatively in assessing the manufacturing performance of a company.