Abstract Network Calculus has been proposed and customized as a framework for worst-case analysis in wireless sensor networks (WSNs). It has been demonstrated that this so-called Sensor Network Calculus (SNC) is an effective network dimensioning tool as it allows us to calculate maximum message transfer delays and communication related energy consumption patterns before network deployment. So far it is unclear how the SNC calculated worst-case delay bounds compare to values experienced in real deployments. Our experiments presented in this paper show that an SNC worst-case delay prediction can be as little as 2.7% above the measured worst-case delay in a typical application scenario. Thus, it can be concluded that the SNC has a very practical relevance for dimensioning wireless sensor networks.