The self-calibrating surface wave transmission method is a promising nondestructive technique for surface-breaking crack depth inspection of concrete. Determination of crack depth using the cut-off frequency in the transmission function (TRF) is difficult, however, in part due to the variability of the measurement data. In this paper the spectral wave-energy transmission method, which employs the self-calibrating configuration, is proposed for crack-depth estimation in concrete structures. Results from an experimental study carried out on a concrete slab with varying crack (notch) depths are reported. The effectiveness of the proposed method is validated by comparing the conventional time-of-flight and cut-off frequency-based methods. The results show that spectral energy transmission has excellent potential as a practical and reliable in-place nondestructive method for in-place crack depth estimation in concrete structures.