When calculating the production costs input data can vary considerably in quality between different cases. When costs pertain from products, which are already in production, complete and reliable data may already be available. For new products, new production systems or new production technology it might be hard to find applicable and reliable data. The cost and performance parameters needed can then be achieved by examining similar products or processes, these parameters will inevitably differ from the new case. The aim of this paper is to try to Monte Carlo simulate production costs, with less reliable data.