Methods and systems that compute an efficiency coefficient of a set of virtual machines (“VMs”) running in a cloud-computing facility are described. The set of VMs may be a collection of VMs that form a VDC or the set of VMs may be a subset of a larger set of VMs that comprises a VDC. The efficiency coefficient is a metric that may be used to evaluate effective use of cloud-computing facility resources by the set of VMs. The efficiency coefficient is calculated based on ideal and actual cumulative cost of the set of VMs utilization of cloud-computing facility resources. As a result, the efficiency coefficient may also be used to assess cost effective use of cloud-computing facility resources by the set of VMs.