A 'feasibility study' is a systematic examination of the worth of a project, or in the case of different projects or different options for the same project, which option is most worthwhile.

The intention is to establish whether or not a project, as outlined in an agreed brief, is a viable proposition. The viability is most often financial but may also be functional. Such an examination is best conducted in the early stages of a project prior to schematic design. The feasibility study should promote rational decision-making processes throughout a project even whilst the building design is evolving. Feasibility studies may be used for a variety of purposes. Foremost, they test and compare the viability of proposals. They are also a vehicle to examine the original brief in detail, prompting discussions of client objectives and the costs implications of various project options, for example the extent of development of notional building plans, or different building envelopes. Feasibility studies can be useful when financial institutions are approached for project funding. There are several types of feasibility studies of differing complexity and reliability. Common to all methods is the identification of project costs and benefits. This procedure requires a number of assumptions to be made about the project and future economic conditions. Most, if not all, costs and benefits are only indicative estimates of future cash flows. The reliability of the feasibility study therefore depends on the validity of the assumptions, the accuracy and precision of the data as well as the type of feasibility study method employed.