A measurement apparatus for measuring an energy quantity flow transported by means of a liquefied natural gas flow , comprising - an ultrasonic measurement device which is configured to measure the flow velocity of the liquefied natural gas flow and the sound velocity in the liquefied natural gas flow based on determined transit times of ultrasonic signals transmitted and received with and against the flow of the liquefied natural gas flow on a measurement path; - a temperature sensor which is configured to measure the temperature of the liquefied natural gas flow ; and - an evaluation unit which is connected to the ultrasonic measurement device and the temperature sensor to receive respective measurement values for the flow velocity, the sound velocity and the temperature, wherein the evaluation unit is configured to determine the volume flow of the liquefied natural gas flow at least based on the flow velocity and the cross-sectional area (F) of the liquefied natural gas flow , to determine the volume-related calorific value of the liquefied natural gas flow at least based on the sound velocity and the temperature by means of a model function, and to determine the transported energy quantity flow based on the determined volume flow and the determined volume-related calorific value, characterized in that the model function is determined based on a data set that specifies the volume-related calorific value of a respective composition for a plurality of different compositions of liquefied natural gas, and in that the model function is an interpolation polynomial that is determined by interpolation of a plurality of support points included in the data set, with the support points specifying a volume-related calorific value determined by calculation and/or experimentally at least for a respective sound velocity and a respective temperature. - an ultrasonic measurement device which is configured to measure the flow velocity of the liquefied natural gas flow and the sound velocity in the liquefied natural gas flow based on determined transit times of ultrasonic signals transmitted and received with and against the flow of the liquefied natural gas flow on a measurement path; - a temperature sensor which is configured to measure the temperature of the liquefied natural gas flow ; and - an evaluation unit which is connected to the ultrasonic measurement device and the temperature sensor to receive respective measurement values for the flow velocity, the sound velocity and the temperature, wherein the evaluation unit is configured to determine the volume flow of the liquefied natural gas flow at least based on the flow velocity and the cross-sectional area (F) of the liquefied natural gas flow , to determine the volume-related calorific value of the liquefied natural gas flow at least based on the sound velocity and the temperature by means of a model function, and to determine the transported energy quantity flow based on the determined volume flow and the determined volume-related calorific value, characterized in that the model function is determined based on a data set that specifies the volume-related calorific value of a respective composition for a plurality of different compositions of liquefied natural gas, and in that the model function is an interpolation polynomial that is determined by interpolation of a plurality of support points included in the data set, with the support points specifying a volume-related calorific value determined by calculation and/or experimentally at least for a respective sound velocity and a respective temperature. <EOS>