The assets of companies is constantly studying for accounting, given its relevance in the business world, since this has direct relation with the financial success of the companies. Accounting began in the early days using rudimentary forms of control of extractivism for the survival of man. The advance of accounting followed the course of time, progressing according to social complexity (productive systems, urban and technological development, population growth, etc.). However, with the technological advance, new accounting perspectives were created, which became an expressive source of information and patrimonial control, among them, fixed assets that are represented by all tangible and intangible assets destined to production or production support. Tangible assets are represented by the machines and equipment which have to measure the operating time over the estimated useful life.The great of estimating the useful life to the reality is linked to the amounts that are shown in the balance sheet, which should not exceed the recovery value of the equipment, be it through sale or cash flow generation. Given the difficulty in determining the useful life of assets with the best possible estimate of their realization, a method was developed that is applicable to any type of equipment.The method starts from a reference value of Reference Useful Life (RUL) that can be obtained through tax legislation, supplier, bibliography, etc. The RUL is altered by some factors that cooperate to increase or reduce the useful life. These factors were created according to the conditions of maintenance, service execution, work environment and the technology involved in the equipment. Each factor is subject to several occurrences called "attributes". The attribute is represented by a value obtained through the application of a questionnaire to the experts who know the equipment. As soon defined the attribute of each factor that best reflects the durability of equipment conditions, it is formed a set of information act to determine the new useful life of the equipment. A set of factors was created, a mathematical equation was created where the Estimated Useful Life (EUL) is obtained through the weighted average of the factors multiplied by the RUL. The application of the method is accomplished through five steps defined in the method: equipment selection, EUL definition, specialist selection, application of the questionnaire to obtain the values of each attribute and application of the information in the mathematical function. The results presented by the method were compared to the useful lives defined by the tax legislation, where they are not appropriated nor accepted by the accounting standards for purposes of equity demonstration. In the use of the study, the results presented by the method were compared to the useful lives defined by the tax legislation, where they are not appropriated nor accepted by the accounting standards for purposes of equity demonstration. The results presented were satisfactory and compatible when compared to reality, but it is recommended to periodically monitor the behavior of EUL, and if distortions were found over the period they should be adjusted and corrected. Finally, the method certified the ability to find 192 EUL distinct from each other, demonstrating that different applications must have different useful lives.