The article discusses the assessment of the complexity and time costs of the staff selection carried out by outsourcing recruitment companies. The objects of the study are to identify factors affecting the complexity of recruiting, to meet the issue of quantitative interpretation of qualitative estimates of the complexity of the work performed, and to develop an empirical dependence of the time spent on staff recruitment. As a result of the work performed, based on expert surveys, the main factors were identified that determine the complexity of the recruitment work, including the employer's reputation capital, recruiting policy, and job placement. For a quantitative interpretation of these estimates, a fuzzy expert system was developed that defines an integral indicator of the complexity of a recruiting order. The dependence of the complexity of the order on the difficulty and size of the order, which allows us to estimate the timing and other costs of recruiting, was revealed. The results of the study can be used to estimate time spent on recruiting personnel, both by recruiting agencies and corporate personnel management and HR departments, which are usually engaged in staff recruitment.