Spinning reserve is idle capacity connected to the system with the purpose of balancing power demand and supply in real-time and ensuring reliable system operations in the case of equipment outages. The re- serve has an economic value since it reduces the load shedding costs. This value is impacted by the reliability and dynamic characteristics of system components, the variability of the load from its forecast, the system operation policies, and economic aspects such as the risk preferences of the demand. In this paper, we take into account all these aspects to estimate the reserve value. The results require little computational effort, and are useful in the development of reserve demand functions and optimal reserve requirements.