The article investigates the author's method of estimating the final cost of a construction investment. A list of proposed methods of calculating the value of the planned final cost of the EAC investment available in the world literature was used. The modification consisted in the first place in the verification and elimination of formulas that do not match the use in construction projects and the combination of formulas resulting in the same result. The study was aimed at enabling the right choice of the method of estimating the final cost of construction investments and determining the accuracy of this estimate. It should be emphasized that the analyzed investments were annexed many times during their implementation. On the basis of the obtained results of research carried out on real construction investments, it was found that 3 methods best predict the final cost of the investment. Finally, improvements were introduced, which were analyzed, the final effect of the article is a proposal of an original, universal formula, which in each of the analyzed construction investments, regardless of the trends, deviations from the cost at the time of the inspection, forecasts the most accurate result, consistent with reality. The conducted research gives the possibility of more effective financial management of a construction investment using the corrected EAC formula in EVM method.