). The numerical data and an estimation of the error for both the alchemical work and the chemical potential are also provided in SI (Tables ). The evolution of the alchemical work as a function of NCMC moves remains constant but displays more fluctuations when the number of electrolyte units increases in the system, leading to higher error calculated for these cases. Overall, errors of the alchemical work calculated for monovalent electrolytes are below of ∼ 1 kJ/mol, except for divalent cations where error reach at most ∼ 4 kJ/mol. Along this line, errors associated with the calculation of the chemical potential are reasonable and reach at most ∼ 5.5 kJ/mol (∼ 1.3 kcal/mol) at high electrolyte concentration. However, the error associated with the calibration process using our method is higher than those of Ross and Chodera for which error of ∆µ NaCl when N NaCl is four times lower than ours. However, our calibration process is rather straightfoward to implement and errors are small enough so that it represents another way for calculating chemical potential in solution with low electrolyte concentration.