ERP clients and vendors necessarily estimate their project interventions at a very early stage, before the full requirements to an ERP solution are known and often before a contract is finalized between a vendor/consulting company and a client. ERP project estimation at the stage of early requirements in a contractual setting has been challenging as it requires the inclusion and the availability of multiple experts, each being a specialist in a particular domain, e.g. solution architect, technical architect, consultant project manager. Today’s highly volatile and customized ERP landscape demands a new approach to estimate effort by leveraging ERP professionals’ tacit knowledge and expert judgments, as well as information from historical project databases (if available). This paper presents three ERP Service estimation strategies that leverage the strengths of both Functional Size Measurement (FSM) and expert-judgment-based estimation techniques. These strategies use a more structur...