Resumo. This research aimed to present a numerical methodology of calculation, based on the Finite Element Method and the Least Squares Method, to determine de longitudinal modulus of elasticity in structural round timber beams, considering the irregularities in the geometry of the elements by linear approximation along the finite elements. In addition with the numerical model (1D), together, two others were used, one analytical (1D simplified), which considers a single value of diameter (cylindrical geometry), measured at the midpoint of the elements, and another numerical model (3D), allows more accurately to delineate the geometry of the element, enabling check the difference between them. Therefore, the beams were evaluated according to the static three-point bending test, being tested twenty four elements of Pinus elliottii wood species, with average length of 630 cm, breast height diameter around 21 cm, green wood (satured), tape average of 6% and mean of factor form section of 0,82. The results of the confidence interval between the modulus of elasticity of the 1D numerical model (Eo) and analytical (Edeq) showed statistical equivalence between the methodologies, justified by the small taper of the elements, may be different for others tapers. The use of the longitudinal modulus of elasticity obtained from de numerical 1D model in the 3D simulations of the round timber beams lead to displacement values equivalent to those obtained in the tests, proving the efficiency of 1D numerical model, requiring less computational work.