A filling and/or charge-amount-monitoring method for a reservoir for storage of a fluid in a cooking device with an inner casing, including a cooking chamber with a fluid inlet and a fluid outlet, a ventilation device with a fan inside the inner casing, for the circulation of a part of the fluid in the inner casing and a control or regulation device, cooperating with the ventilation device and/or a filling and/or charge-amount-monitoring device, whereby a characteristic parameter for the ventilation device, changing on the basis of the force exerted by the fluid incident on the fan, is analyzed by the filling and/or charge-amount-monitoring device and may be rotation speed, power or current consumption of the ventilation device and a cooking device with a filling and/or charge-amount-monitoring.