Total THC

USDA's hemp production rules define total THC as delta-9 THC plus 0.877 times THCa, measured after decarboxylation or calculated from a liquid chromatography result (7 CFR 990.1). The 0.877 factor is the mass ratio between THC and its acid, because the acid loses carbon dioxide when heated.

Crop testing under USDA plans has used total THC since the program started. The federal hemp definition for finished products did not, until section 781 of Public Law 119-37 rewrote it to say total tetrahydrocannabinols concentration, including tetrahydrocannabinolic acid, of not more than 0.3 percent on a dry weight basis (7 U.S.C. 1639o). Public Law 119-103 held that change back until December 11, 2026 (P.L. 119-103).

For final products the statute adds a second test: no more than 0.4 milligrams combined total THC and similar cannabinoids per innermost container. A 30 mL full-spectrum tincture at the plant limit can exceed that figure, which is why isolate and broad-spectrum products with non-detect THC became the compliance core.

UPS will require a certificate of analysis showing total THC at or below 0.3 percent for raw hemp starting December 11, 2026 (UPS).