The shear strength of soils is key design property that governs the stability of geotechnical structures. For clays, the undrained shear strength is commonly adopted in design, while the friction angle is a soil property that represents the shear strength of sands. Estimation of these properties is a challenging task, and the challenge is even greater for sandy soils since the strength is highly state-dependent and undisturbed soil sampling is difficult. As a result, various empirical correlations based on in-situ test results, such as SPT and CPT, have been proposed. However, further investigation is still necessary for the consideration of the state-dependent dilatancy and soil constitution. In the present study, a CPT-based method for the estimation of the in-situ strength for granular soils is investigated. Various field variables such as fines content, soil density and confining stress are considered. A series of laboratory test results obtained for various soil conditions are used in the analysis and investigation.