Geocells are geosynthetics applied as reinforcements on shallows foundations and pavements, and have others uses in geotechnical and hydraulics engineering. Its structure confines the infill soil, (usually granular), generating a layer with an improved behavior in terms of resistance (ultimate state) and displacements (service state). A possible methodology to modeling this geocell-reinforced layer is considering it as a composite with equivalent geomechanics parameters that is over the foundation or subgrade - which is usually a soil with reduced resistance/stiffness. This kind of situation configures a two-layer system, treated mathematically by the theory of elasticity (TE) - rigorous form - proposed by Burmister (1943) and by the theory of equivalent thickness (TET) - approximated method - proposed by Palmer and Barber (1940), Odemark (1949) and, recently, by Avesani Neto (2019). In this aspect, this article performs a comparison between these theories and a multilayer analysis software evaluating the applicability and accuracy of these methods, especially considering the usual variations of the problem: geometry and of the elastic parameters. The analysis shows that the approximated solutions by TET gives compatibles results comparing with the rigorous formulation and with the software, proving viability of its application mainly by the reason to be simple and easy to employ.