Various technical solutions are available for condition monitoring (CM) of wind farms. The technical and economic benefits of CM systems are the subject of debate between manufacturers and operators. Manufacturers state that CM systems lower operation costs via optimised maintenance scheduling and resource management. Operators are keen for the techno-economic benefits to be demonstrated before they switch from time-based maintenance to condition-based maintenance. In particular, the merits of monitoring individual sub-components are unclear. This article presents a method that has been developed to estimate the techno-economic benefits of individual wind farm CM options based on a combination of industry experience and publicly available data.