Abstract: Recent terrorist activities have rekindled an interest in studying the local damage of reinforced concrete (RC) structures subjected to explosion or impact loads. Scabbing is one of three types of local damage of RC structures. It is also the major factor that influences the resistance of RC structures to the local damage. In this paper, the presently widely-used formulae of the scabbing thickness of RC structures are compared with the test data and analyzed. The application range and the predicting error of each empirical formula is obtained. It is concluded that, the predictions of Bechtel formula and modified BRL formula fit best with the test results. The Bechtel formula can be used to predict critical scabbing thickness, and the modified BRL formula can be used to predict the critical penetration thickness.