To provide a proper infrastructure and an adequate level of staffing are two strategic challenges for prison agencies. Both building prisons and recruiting/training of staff are time consuming activities which need long term planning. Forecasting is a method to calculate future demand for prison capacity. What is promoted in this area today is “chain thinking”, which means including changes and forecasts made in each part of the chain of justice, including changes in crime levels. Awareness of such chain effects is one of the gains of using forecasting models. Forecasts can be used to increase transparency in budget preparations, as well as create an understanding for chain effects among politicians and other decision makers.