CBD vaporisation temperature: what the measurements say

Nearly every table found online reproduces a 2001 review by McPartland and Russo, published in the Journal of Cannabis Therapeutics. Its tables of cannabis constituents list a "boiling point" for each molecule: 157 °C for THC, 160 to 180 °C for CBD, 185 °C for CBN and 220 °C for CBC. A note says the values apply at atmospheric pressure unless stated otherwise.

The THC value breaks that rule. A 2025 study in the Journal of Cannabis Research followed the figure to its origin: 157 °C is the temperature at which chemists distilled THC under a strong vacuum (0.05 Torr) in work published in 1941 and 1964. Using thermogravimetric analysis, the authors measured the boiling point at normal pressure at about 245 °C. As far as we know, nobody has published the same measurement for CBD, so its 160 to 180 °C still has no verifiable source.

The terpene values in the table mostly hold up, with one exception. We checked them against PubChem, a database that compiles reference data at 760 mmHg.

Beta-caryophyllene follows the same pattern as THC. PubChem lists a boiling point near 130 °C at a reduced pressure of 14 mmHg and near 256 °C at normal pressure. The 119 °C figure therefore also appears to come from a measurement under vacuum. Our article on beta-caryophyllene introduces this terpene.

A molecule turns into vapour well before its boiling point: a puddle dries at 20 °C without ever boiling. Cannabinoids behave the same way and evaporate faster as the temperature climbs. That is why a vaporiser set to 200 °C releases THC and CBD even though both boil higher.

Heat has a second effect. Most of the CBD in the flower is present as CBDA, its acidic form, which becomes CBD once it loses a carboxyl group. At these temperatures the conversion is close to instant. The reaction is explained in our article on decarboxylation.

The earliest published study is from 2004. Gieringer and colleagues heated 200 mg cannabis samples between 155 and 218 °C in a tabletop device and compared the vapour with smoke. Their article in the Journal of Cannabis Therapeutics reports that the device delivered 36 to 61% of the sample's THC. Besides cannabinoids, the gas phase of the vapour held three other compounds in trace amounts, while the smoke held more than 111, polycyclic aromatic hydrocarbons among them. The authors put the onset of combustion near 230 °C. Part of the funding came from groups campaigning for cannabis law reform and from the maker of the device.

In 2016 a Swiss team published a validation of five vaporisers in PLOS One, testing both THC-rich and CBD-rich flowers. Four electric models ran at 210 °C. The fifth was heated by gas and had no temperature control.

The electric models converted at least 94.6% of the acids into neutral forms. The gas device reached 87.7 to 93.3% and was the only one with visible signs of combustion. Temperature control counts for more than the format of the device.

A Dutch study from 2009 contradicts a widespread belief. In a tabletop vaporiser, vapour produced at 170 °C had the worst ratio of cannabinoids to by-products, whereas at 200 and 230 °C it beat cannabis cigarette smoke by a clear margin. Lowering the temperature does not automatically make the vapour "cleaner".

No study has compared settings for CBD on its own. Until one does, the work cited above supports a cautious approach: begin around 185 to 200 °C, raise the setting to 210 °C only if you need to, and keep well below 230 °C. The 2004 team ran its device at 202 °C. It also reports that an earlier study of theirs, on another model, found an optimum near 185 °C and detected toxic compounds above 200 °C.

• Under 180 °C, CBD comes off more slowly, and the one measurement available, taken at 170 °C, is unfavourable.
• From 185 to 210 °C you are where most of the studied settings sit. Terpenes, which mostly boil between 155 and 200 °C, come off as well.
• Past 210 °C you get closer to combustion, which the 2004 authors locate near 230 °C.

Then comes the choice between conduction and convection. Conduction heats the material by contact with a hot surface, and convection sends hot air through it. The 2016 study leaves the question open, since its clearest gap lay between the temperature-controlled devices and the uncontrolled gas model. With a CBD flower, an even grind helps the heat spread. Resin needs other settings and other cleaning, covered in our article on hash in a vaporiser, and the one on useful accessories can help you pick equipment.

Every flower vaporiser has a heat source, a chamber for the material and an air path leading to the mouthpiece. What sets devices apart is how the heat travels to the flower.

With conduction, the chamber heats up and passes that heat to the flower through contact. The layer touching the wall warms first, and the centre of the chamber catches up more slowly. An even grind and a uniform fill therefore spread the heat better. The material also goes on heating between draws, because the wall stays hot.

With convection, an element heats the air, which then flows through the flower. The heat reaches the whole volume instead of working in from the edges, as long as air is moving. The flower therefore heats mostly during the draw, or while a fan blows air on tabletop devices that fill a balloon. A grind that is too fine or packed too tight slows the flow.

Many devices use both principles. Whatever the type, the displayed temperature is what the device's sensor reads at its own position, which may differ from the temperature of the flower. The studies cited above report set temperatures, so the 185 to 210 °C range refers to the display and was never measured inside the material.

The studies describe fewer combustion compounds, and some remain. The 2016 authors note that vaporisation aims to avoid tar, polycyclic aromatic hydrocarbons, carbon monoxide and benzene, and they stop short of calling inhalation harmless. None of these studies examined long-term health effects.

Two further points. Vaporising a flower is a different practice from vaping an e-liquid, where solvents and flavourings are heated by a coil; our article on dosing CBD e-liquids deals with that format. Heat also converts the THCA in a compliant flower into THC, so the vapour carries traces of it even when the flower stays within the 0.30% Δ⁹-THC limit.