The hemispherical total emissivity of two thermal control coatings, Z-93-P and black anodized aluminum, was calculated from hemispherical total reflectivity measured in the wavelength range of 2 to 40 mu m. These data were compared to hemispherical total emissivity values obtained on the same samples measured in a thermal vacuum chamber with a calorimetric technique. The comparison showed clos agreement in the vicinity of room temperature and above, with differing trends at lower temperatures.