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CBD decarboxylation calculator

The duration that turns the most CBDA into CBD at a given temperature, from the published rate constants, and what the heating loses.

A laboratory oven on a bench, its two dials on top: the thermostat, whose needle stands at the chosen temperature, and the timer, at the advised duration. On the right, two graduated cylinders before a ruled board: the CBDA still acidic and, in pink, the CBD formed.

The oven

The thermostat reads 50 to 250 °C, the timer 0 to 180 minutes. The board's lines mark 25, 50, 75 and 100 % of the starting CBDA.

52 min

78 % of the CBDA becomes CBD; the rest is lost on the way or stays acidic.

Temperature of the material

The material's own temperature, to check with a thermometer: a home oven often strays from its setting.

Product profile

The rates on the batch's certificate of analysis, as a percentage of the material.

After 52 min at 110 °C

CBDA still acidic7.7%
CBDA turned into CBD77.6%
Lost on the way14.8%
CBD in the material after heating7.6%
Theoretical total CBD (CBD + 0.877 × CBDA)9.8%

Milestones at this temperature

Half of the CBDA converted14 min
90 % of the CBDA converted46 min
95 % of the CBDA converted60 min

Method and limits

The rate constants come from Wang and colleagues (Cannabis and Cannabinoid Research, 2016), who heated flower extracts in a thin layer, in a vacuum oven, between 80 and 145 °C. For CBDA: 0.83 × 10⁻³ s⁻¹ at 110 °C and an activation energy of 112 kJ/mol, from which the Arrhenius law gives the other temperatures. At 110 °C, half of the CBDA is converted in 14 minutes and 95 % in about an hour.

The reaction is not clean: by the end, the CBDA + CBD sum had lost 18 % at 110 °C and 25 % at 130 °C. The model puts that loss on the CBD once formed and fits it to those two measurements. Since it grows faster with heat than the decarboxylation does, each temperature has a duration that gives the most CBD, and a gentler heat keeps more of it. Seo and colleagues (Journal of Analytical Science and Technology, 2022) also observed, at 130 °C, a partial cyclisation of CBD into THC isomers.

The mass of CBD obtained is 0.877 times that of the CBDA decarboxylated (314.5 over 358.5 g/mol): it is the “total CBD = CBD + 0.877 × CBDA” rule of certificates of analysis. Further reading: what temperature, and for how long, and the CBDA entry in the Canna·wiki.

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