A method for determining at least one parameter of an extracorporeal blood circuit includes the steps of filling an extracorporeal blood circuit, e.g., encompassing a medical functional device, a treatment device and/or a blood tube set, by introducing a fluid, and detecting a volume of the introduced fluid which is required for filling the extracorporeal blood circuit by a detection device. A control device, a treatment apparatus, a computer readable storage medium, a computer program product as well as a computer program are also described.