Iowa Code Title V. Agriculture [Chs. 159-215A] § 210.4. Weight

The units or standards of weight from which all other weights shall be derived and ascertained shall be the standard avoirdupois and troy weights secured in accordance with the provisions of section 210.1. The avoirdupois pound, which bears to the troy pound the ratio of seven thousand to five thousand seven hundred sixty, shall be divided into sixteen equal parts called ounces; the hundred-weight shall consist of one hundred avoirdupois pounds, and twenty hundred-weight shall constitute a ton. The troy ounce shall be equal to the twelfth part of a troy pound.