41 U.S.C. § 3310

(a) Factors Affecting Quantity To Order .— Each executive agency shall procure supplies in a quantity that— (1) will result in the total cost and unit cost most advantageous to the Federal Government, where practicable; and (2) does not exceed the quantity reasonably expected to be required by the agency. (b) Offeror’s Opinion of Quantity .— Each solicitation for a contract for supplies shall, if practicable, include a provision inviting each offeror responding to the solicitation to state an opinion on whether the quantity of supplies proposed to be procured is economically advantageous to the Federal Government and, if applicable, to recommend a quantity that would be more economically advantageous to the Federal Government. Each recommendation shall include a quotation of the total price and the unit price for supplies procured in each recommended quantity.