A method of determining the fuel consumption of an internal combustion engine 12, more particularly when operated on a test rig, wherein fuel is supplied in a circuit to the internal combustion engine and discharged therefrom and wherein a quantity of fuel is supplied to the circuit 11 via a branch line 22 from a fuel tank 23 and measured in the branch line, wherein temperature-related changes in the volume of the fuel are determined in the circuit 11 and wherein the consumed quantity {dot over (m)}S determined in the branch line 22 is corrected by a corrective quantity {dot over (m)}K corresponding to the temperature-related changes in volume in the circuit.