THC to THCa
Enter your target THC mass to find the equivalent starting THCa.
Input parameters
Starting or target mass
Equation
Calculation method Equation, inputs and limitations
Calculating required starting THCa
Planning starts from the desired theoretical THC mass. Because each mole of THCa loses one molecule of CO2 during decarboxylation, divide the target THC mass by the ratio 314.46 ÷ 358.47 (approximately 0.87723) to obtain its THCa mass equivalent. For example, 10 g of target THC corresponds to approximately 11.399 g of pure starting THCa.
The result assumes complete conversion without additional losses. This is not a chemical conversion of THC into THCa, and practical starting masses depend on assay purity, reaction completion, degradation, and material recovery.
Questions & limitations 3 answers
How much pure THCa is needed for 1 gram of theoretical THC?
About 1.140 grams of THCa. Divide the intended THC mass by the THCa-to-THC molar-mass ratio, 314.46 ÷ 358.47 (approximately 0.87723). For 10 grams of theoretical THC, the equivalent starting THCa mass is approximately 11.4 grams.
Does this calculator chemically convert THC into THCa?
No. It solves the forward decarboxylation equation in reverse to estimate required starting acid mass. It does not describe a reaction that adds CO2 back to THC.
Does the required THCa mass include material losses or incomplete conversion?
No. This is a theoretical mass equivalence for pure THCa with full conversion and full recovery. Assay purity, incomplete reaction, transfer losses and degradation can increase the starting amount needed to reach a measured THC target.