Managing and running business processes in the Cloud changes how Workflow Management Systems (WfMSs) are deployed. Consequently, when designing such WfMSs, there is a need of determining the sweet spot in the performance vs. resource consumption trade-off. While all Cloud providers agree on the pay-as-you-go resource consumption model, every provider uses a different cost model to gain a competitive edge. In this paper, we present a novel method for estimating the infrastructure costs of running business processes in the Cloud. The method is based on the precise measurement of the resources required to run a mix of business process in the Cloud, while accomplishing expected performance requirements. To showcase the method we use the BenchFlow framework to run experiments on a widely used open-source WfMS executing custom workload with a varying number of simulated users. The experiments are necessary to reliably measure WfMS’s performance and resource consumption, which is then used to estimate the infrastructure costs of executing such workload on four different Cloud providers.