Total THC
Also known as: Total Delta-9 THC
Total THC counts the delta-9 THC already in a product plus the THC its THCA would become if heated — calculated as (0.877 x THCA) + delta-9 THC.
Hemp carries most of its THC in an acid form, THCA, which is not intoxicating until heat converts it. A delta-9-only measurement therefore understates what a product can turn into. The total-THC formula closes that gap by multiplying THCA by 0.877 and adding the delta-9 already present. The 0.877 is straight chemistry, not policy: decarboxylation sheds a carboxyl group as carbon dioxide, and THC's molar mass (314.46 g/mol) divided by THCA's (358.47 g/mol) is 0.877, so a gram of THCA can only ever become 0.877 grams of THC. USDA has required this calculation for hemp crop compliance since its final rule took effect March 22, 2021.
The number matters more in 2026 than it used to. Section 781 of P.L. 119-37 rewrites the federal hemp definition around total THC instead of delta-9 alone, and caps a finished consumer product at 0.4 mg of total THC per container as sold — per bottle, not per serving. H.R. 6500, signed September 2, 2026, split the timing: cannabinoids the plant cannot produce naturally, like delta-8 and THC-O, lose federal hemp status on November 12, 2026, and the total-THC standard plus the container cap follow on December 11, 2026.
On a COA, look for a Total THC row rather than only a Delta-9 THC row. The two answer different questions. A full-spectrum 30 mL bottle sits comfortably under 0.3% delta-9 by weight and still carries far more than 0.4 mg of total THC in the container. Broad-spectrum and THC-free products are not affected by the cap.
Related terms
- THCA (Tetrahydrocannabinolic Acid)THCA is the raw, non-intoxicating acid form of THC that the living hemp plant actually produces. Heat converts it into delta-9 THC.
- THC (Tetrahydrocannabinol)THC is the cannabinoid responsible for the psychoactive 'high' associated with marijuana. Hemp-derived CBD products may contain up to 0.3% THC under federal law.
- DecarboxylationDecarboxylation is the process of converting raw cannabinoid acids (like CBDa) into their active forms (like CBD) by applying heat.
- COA (Certificate of Analysis)A COA is a document from an accredited third-party lab certifying what is — and isn't — in a CBD product.
- 2018 Farm BillThe 2018 Farm Bill federally legalized hemp by removing it from the Controlled Substances Act. It defines hemp as cannabis with under 0.3% delta-9 THC.