To achieve rapid and accurate estimation of the shear strength indicators of calcareous sand under emergency conditions, drained triaxial tests were conducted to investigate the strength and dilatancy characteristics of uncemented calcareous sand. By varying the relative density and effective confining pressure of specimens, the factors influencing the internal friction angle of uncemented calcareous sand were analyzed, and empirical formulas were proposed to accurately predict the peak internal friction angle and dilatancy angle of uncemented calcareous sand. The test results show that the peak internal friction angle and dilatancy angle of calcareous sand are significantly affected by relative density. The formula parameters modified based on the test data can improve the prediction reliability for the peak internal friction angle and dilatancy angle of uncemented calcareous sand. The prediction errors of the peak internal friction angle are mostly less than 25%. The empirical formulas can be used for rapid estimation of the shear strength indicators of uncemented calcareous sand specimens with a post-consolidation relative density ranging from 31% to 83% and a mean effective normal stress at the stress peak ranging from 100 kPa to 1 600 kPa.