This paper develops formulas to provision bandwidth for any number of high speed internet subscribers at a given probability that load exceeds available capacity. Formulas are based on Gamma models fitted to traffic loads generated over 1-sec intervals by various subscriber aggregations. We assume loads are i.i.d. and use characteristic function properties to extrapolate load distributions for any aggregation size. The provisioning formulas show that economies of scale exist. Results apply to initial system provisioning and to growth planning in existing networks. Sensitivity analysis is performed. Findings may interest telephone and cable companies.