The current tool estimates the deformation modulus or modulus of elasticity of soft rock based on Hoobs (1974) mass factor theoretical equation. It requires as an input the unconfined compressive strength of rock from UCS laboratory tests and RQD values from coring. The equation also requires an estimate of the modulus ratio value, Mr, to account for rock type.

Based on RQD, the equation calculates the mass factor j, to account for rock mass discontinuities, fractures, and weathering and the modulus ratio value, M, to account for rock type.