Labs · Updated 2026-11-14
Reading a certificate of analysis
What the lab report on a product tells you, what it does not and the one calculation that explains THC versus THCA.
What a certificate of analysis is
A certificate of analysis (COA) is a lab report on one batch of a product. It tells you what that laboratory found in that batch on that date.
What to look for
- The lab: its name and its accreditation, which you can check with the accrediting body.
- The batch: the number should match the product in your hand.
- The date: when it was analysed.
- The method: what was measured and how.
- The result: THC, THCA and other cannabinoids, plus any contaminants the lab reports on.
THC versus THCA
Raw flower contains mostly THCA, which is not intoxicating. Heat removes a carboxyl group as carbon dioxide and leaves THC. THCA has a molar mass of about 358.5 g/mol and THC about 314.5 g/mol (PubChem), so one gram of THCA can become at most 0.877 g of THC. "Total THC" on a report is usually THC plus 0.877 times THCA.
What a COA does not tell you
- How strong a portion of a homemade food will be.
- Whether the batch you hold is the batch that was analysed, unless the numbers match.
- Anything about health effects.
- PubChem, National Library of Medicine: Dronabinol (THC), CID 16078, pubchem.ncbi.nlm.nih.gov/compound/16078; Tetrahydrocannabinolic acid, CID 98523, pubchem.ncbi.nlm.nih.gov/compound/98523.
- Leafly, How to make cannabutter (applies an 87.7% THCA to THC conversion), leafly.com/learn/consume/edibles/how-to-make-cannabutter.
