Since the first images from the sensors onboard CBERS-2 (China-Brazil Earth Resources Satellite) were made available by the National Institute for Space Research (INPE), users have requested information about the conversion of image digital numbers into physical data ( radiance or reflectance). This Letter describes the main steps that were carried out to calculate the in-flight absolute calibration coefficients for CBERS-2 Infrared Multispectral Scanner (IRMSS) level 2 ( radiometric and geometric correction) images considering the reflectance-based method. Remarks about the preliminary evaluation of the application of these coefficients are also presented.274799804