Ounce (28g)

An ounce (avoirdupois, oz) is the imperial unit of mass equal to exactly 28.349523125 g (1959 International Yard and Pound Agreement). In U.S. cannabis retail and regulation, the ounce is conventionally rounded to 28 g for packaging, labeling, and traceability (Metrc, BioTrack). Colorado, Washington, Oregon, California, and Massachusetts all set recreational adult possession at "1 oz of usable cannabis," with state rules defining equivalencies (e.g., Colorado: 1 oz flower = 8 g concentrate = 800 mg edible THC). Note — disputed value: The true avoirdupois ounce is 28.35 g; the cannabis-retail "ounce" of 28 g is ~1.2% short, creating small systematic discrepancies between imperial-labeled possession limits and metric-tracked inventory.