What decarboxylation actually does
Raw cannabis contains almost no THC. It contains THCA — tetrahydrocannabinolic acid — which does not get you high. Applying heat over time breaks a carboxyl group off the molecule, releasing carbon dioxide and leaving THC behind. That reaction is decarboxylation, and it is the step that turns plant material into something worth infusing.
Smoking does this instantly at combustion temperature. Edibles do not have that luxury, which is why raw flower stirred into butter produces a disappointing batch.
Why it costs you mass
The carbon dioxide that leaves takes weight with it. THCA weighs 358.47 g/mol and THC weighs 314.46 g/mol, so even a flawless decarb yields 0.877 grams of THC per gram of THCA. That is not inefficiency you can optimise away; it is stoichiometry. The edible dosage calculator applies this factor automatically when you tell it your label reports THCA.
Where these numbers come from
Decarboxylation is a first-order reaction, and first-order rate constants follow the Arrhenius relationship — meaning the logarithm of the time required is linear in the reciprocal of absolute temperature. This calculator fits that relationship to the time and temperature pairs that home-decarb guidance has converged on, then uses it to interpolate any combination you enter.
Two honest caveats. First, those published anchors are rules of thumb and are not perfectly consistent with each other, so the fit reproduces them to within about 14% rather than exactly. Second, the implied activation energy comes out lower than laboratory kinetics for isolated THCA — which is expected, because oven guidance absorbs preheat lag, tray depth and thermal mass that a sealed laboratory vial does not have.
In short: this is a well-calibrated starting point, not a lab protocol. The single biggest improvement you can make to your own accuracy costs about ten dollars and is an oven thermometer.
Step by step
- Preheat properly. Wait for the oven to fully stabilise. Starting the timer early is the most common mistake.
- Break it up by hand. Roughly rice-sized. Do not grind to powder — fine material scorches and passes more chlorophyll into your infusion.
- Thin, even layer. Piled material decarbs unevenly, leaving the middle under-converted.
- Cover with foil. Retains terpenes and stops light material moving around.
- Stir once at the halfway point. Gently.
- Cool completely before infusing or storing.
Common mistakes
- Too hot. Above 300°F, THC degrades to CBN faster than THCA converts to THC. You end up with a sleepy, weaker batch.
- Trusting the dial. Home ovens routinely run 25°F off. This is the largest single source of error in the whole process.
- Grinding too fine. Increases scorching and chlorophyll extraction.
- Skipping it for concentrates. Distillate is already decarbed. Heating it again just degrades it.