Presented at the 2013 Aquarius/SAC-D Science Team MeetingThe MWR Calibration Team has developed an improved Microwave Radiometer (MWR) algorithm (version 6) to convert the radiometric counts to brightness temperature (Tb). This algorithm is based upon rigorous radiative transfer models with empirically derived coefficients from both pre-launch thermal vacuum radiometric calibration testing and on orbit intersatellite cross calibrations (XCAL) with the Naval Research Lab's WindSat satellite radiometer. This poster presents recent results of on-orbit MWR/WindSat XCAL comparisons for the newest version 6 of the MWR counts to Tb algorithm, which includes a "counts linearization" procedure to correct for a small radiometer non-linearity. To develop a linear radiometer transfer function, we analyzed MWR on orbit Tb measurements that includes Cold Sky Calibration (CSC) and ocean and land observations to provide a wide dynamic range of brightness temperatures. The analysis procedure is described, which includes normalization of the on orbit gain changes due to physical temperature changes. XCAL validation results of the previous version 5 and the new version 6 algorithms are shown for one year of comparisons between MWR and WindSat.