The lack of a proper decision variable impedes the planning of dimensional stone quarry operation. So far, "quasi-grade", which may measure the stone quality, developed via multivariate statistical methods is offered as decision variable. However, the marketable blocks of dimensional stones should satisfy not only stone quality requirements, but also conform to certain dimensional standards, and these two are essentially incommensurable. Clearly, for stone with known quality, the amount of marketable dimensional stones (MDS) provides the best decision variable for planning (i.e. sequencing the operation of unit volumes). A method for determining the amount of MDS before actual extraction is presented.