The present study developed a mechanistic approach for computing the resilient modulus of subgrade using the elastic theory of one-layer structure. The stress function for the structure was solved and then the expressions of stresses and deformations were derived using Hankel transform. The derivation was incorporated in MATLAB to develop a computer program ‘moduli’ which could compute the vertical deformation at any point. Validation of the derivation was done based on the close agreement between the vertical deformation computed by the moduli, Plaxis 2D and IITPAVE computer program. A statistical correlation was developed between the vertical surface deformation in the axis of symmetry computed by the moduli program under confined condition and half-space condition. For the assumed vertical surface deformation of 0.1, 0.2, 0.3, 0.4, 0.5 and 0.6 mm in the axis of symmetry under confined condition, the statistical correlation was used to compute the same under half-space condition. Corresponding to each of these deformation, the moduli program computed the resilient modulus of 451.3, 225.7, 150.5, 112.8, 90.3 and 75.2 MPa under half-space condition. Using the computed resilient modulus, the Plaxis 2D program computed the vertical surface deformation in the axis of symmetry under confined condition. The agreement between the computed deformations and the assumed deformations with a coefficient of determination (R2) of 1.0 depicts the acceptance of the computed resilient modulus. This established the ability of the proposed method to compute the resilient modulus of subgrade soil under half-space condition.