This article addresses the issue of dynamic pricing strategy, which currently is widely spread in the e-commerce markets. The air transport industry was one of the first segments of the Internet-market in which dynamic pricing model was implemented. The scope of the research is the market of low-cost carriers. The subject-matter of the study is the strategy of dynamic pricing according to the «low expenses» system in the air passenger market. The paper presents the mathematical model for determining an optimal price on the certain day of the year in low-cost airlines. The results indicate the parameters that influence the ticket price are the number of days between the reservation day and the flight day, the level of booking, the time of buying a ticket. Knowledge of these variables allows a low-cost carrier to define an optimal ticket price.