Interactive calculator
THCA to THC conversion calculator
Estimate potential THC after decarboxylation using the standard educational conversion factor of 0.877.
What is THCA?
THCA (tetrahydrocannabinolic acid) is the raw, non-intoxicating form of THC found in fresh and dried hemp flower. It does not produce psychoactive effects on its own. When heated — through smoking, vaping, or cooking — THCA undergoes decarboxylation and converts into delta-9 THC, which is the active compound responsible for the effects most people associate with cannabis.
Where does 0.877 come from?
The 0.877 conversion factor comes from the molecular weight difference between THCA and THC. THCA has a molecular weight of 358.5 g/mol. When it loses a carboxyl group (CO₂) during decarboxylation, it becomes THC at 314.5 g/mol. Dividing 314.5 by 358.5 gives approximately 0.877 — meaning roughly 87.7% of the THCA by weight converts to THC under ideal conditions.
How to find THCA % on a COA
A Certificate of Analysis (COA) from an accredited lab will list THCA as a percentage of the total sample weight. Look for a line labeled "THCA" in the cannabinoid panel — not "Total THC," which is a calculated figure. The raw THCA percentage is what you enter into this calculator. Reputable vendors publish current COAs on their product pages or provide a QR code on the packaging.
Real-world limitations
This calculator assumes complete, ideal decarboxylation. In practice, conversion is never 100% efficient. Combustion (smoking) typically converts 60–80% of available THCA. Vaping varies by temperature — lower temps preserve terpenes but convert less THCA. Cooking or baking at controlled temperatures can approach the theoretical maximum but still varies by time, heat distribution, and fat content. Use this estimate as an educational reference, not a precise dosing tool.