Abstract. This article generalizes joint work of the first author and I. Swanson to the s-multiplicity recently introduced by the second author. For k a field and X = [x i,j ] a m × n-matrix of variables, we utilize Gröbner bases to give a closed form the length, q is a sufficiently large power of p, and m is the homogeneous maximal ideal of k [X]. This shows this length is always eventually a polynomial function of q for all s.