Madter thesis about cost functions in company deal with especially issues of costs depend on the production scale, issues of determination of cost functions, also imagine such as issues of calculation fixed and variable costs or aplication cost functions through break even point. Master thesis is divided into six chapter. Introductory chapter pay attention to classificatipn cost depend on the production scale. These kind of cost are divided into other groups of cost. Next chapter is dedicated to methods of determination cost functions. Later these methods will be used in practical part of master thesis at determination cost functions. Fourth chapter is about aplication of cost functions. Final thesis also contains metodics and objectives of thesis. The final chapter presents practical part of these thesis about aplication cost functions in company. This section is focused pn determination cost functions and chris r aplication for determination break even point our selected company. At the end of master thesis rate quantity of fixed costs, variable costs and break even point. In this part of thesis pay attention not only but also points to differences of determination cost functions through methods of determination fixed and variable costs.