Method for determining a performance index of a cooking receptacle (1a, 1b) subjected to a heating power generated by heating means, said index representing the capacity of said cooking receptacle (1a, 1b) to distribute the heating power homogeneously throughout the whole cooking receptacle over the course of time necessary for cooking food, said cooking receptacle (1a, 1b) comprising a bottom and a side wall provided with an external face, characterised in that it comprises the following steps: a) subjecting the bottom of the cooking receptacle (1a, 1b) to the heating means started up at a given heating power, the heating of the bottom causing a rise in the temperature of the external face of the side wall, b) measuring and recording at regular time intervals the temperature at least three points (17, 18, 19) at a predetermined height on the external face during the heating of the cooking receptacle (1a, 1b) until at least one of the measured temperatures stabilises, c) calculating and recording, during the rise in temperature of the external face, the difference between the maximum temperature and the minimum temperature measured at each time interval at the at least three points (17, 18, 19), d) determining the performance index from the calculations and recordings made at step c), that is to say - at step d), the greatest difference is determined among the differences between the maximum temperature and the minimum temperature recorded at each time interval at step c), the performance index of the cooking receptacle (1a, 1b) being equal to said greatest difference, or - at step d), the average is calculated of the differences between the maximum temperature and the minimum temperature recorded at each time interval during the rise in temperature of the external face, the performance index of the cooking receptacle being equal to the average. a) subjecting the bottom of the cooking receptacle (1a, 1b) to the heating means started up at a given heating power, the heating of the bottom causing a rise in the temperature of the external face of the side wall, b) measuring and recording at regular time intervals the temperature at least three points (17, 18, 19) at a predetermined height on the external face during the heating of the cooking receptacle (1a, 1b) until at least one of the measured temperatures stabilises, c) calculating and recording, during the rise in temperature of the external face, the difference between the maximum temperature and the minimum temperature measured at each time interval at the at least three points (17, 18, 19), d) determining the performance index from the calculations and recordings made at step c), that is to say - at step d), the greatest difference is determined among the differences between the maximum temperature and the minimum temperature recorded at each time interval at step c), the performance index of the cooking receptacle (1a, 1b) being equal to said greatest difference, or - at step d), the average is calculated of the differences between the maximum temperature and the minimum temperature recorded at each time interval during the rise in temperature of the external face, the performance index of the cooking receptacle being equal to the average. - at step d), the greatest difference is determined among the differences between the maximum temperature and the minimum temperature recorded at each time interval at step c), the performance index of the cooking receptacle (1a, 1b) being equal to said greatest difference, or - at step d), the average is calculated of the differences between the maximum temperature and the minimum temperature recorded at each time interval during the rise in temperature of the external face, the performance index of the cooking receptacle being equal to the average.