The present recommendation of the GEFTA working group "Calibration of Scanning Calorimeters" allows a precise heat and heat flow rate calibration of scanning calorimeters, largely independent of instrumental, sample-related and experimental parameters. Electric energy, electric power, heats of transition and heat capacities of suitable calibration substances are used for calibration. The measuring method, measuring and evaluation procedure, calibration materials, significant influencing factors, sources of error and detailed examples are presented for these calibration methods. Besides specific problems of heat measurement (interpolation of the baseline for the peak area determination) and heat capacity measurement (interpolation between initial and final isotherms, determination of the true heating rate of the sample, thermal lag of the sample), general aspects (thermodynamic fundamentals, difference between heat and heat flow rate calibration factor, weighing procedure) are also discussed.