Abstract: This paper summarizes some test and theoretical results and evaluates several experimental formulas for estimating the penetration and scabbing limit thickness of concrete targets under projectile impact. The parameters of four types of missiles with different characteristics and concrete targets are given. The corresponding penetration and scabbing limit thicknesses are calculated under different velocities. The results indicate that there are minor difference in estimating penetration but significant difference in estimating scabbing limit thicknesses using existing experiential formulas.