Abstract This paper proposes an accurate estimation for the experimental thermodynamic performance of a Single Stage Absorption Heat Transformer (SSHT). The calculation includes five heat and mass transfer effectiveness factors of the components in the SSHT. The evaporator, condenser and heat exchanger effectiveness is based on the method of Number of transfer units (NTU). Absorber and generator effectiveness are correlated with mass transfer, concentrations of the working mixture, and external powers, respectively. Calculations according to the operating conditions of the experimental tests were carried out in a 4 kW absorption heat transformer. The experiment was performed with the water/Carrol mixture with concentrations from 66 to 69%w; the actual Coefficient of Performance (COP a ) values were from 0.28 to 0.35, while the classical model overestimates these values from 0.47 to 0.49, respectively. The predicted COPη with these effectiveness factors is much more accurate (error factor lower than 92.25%) with COP a .