Cannabinoid Boiling Points: Why the Common Numbers Are Wrong

Last updated on August 16, 2026 · Originally published January 24, 2023

The most-quoted number in cannabis vaporizing is a vacuum distillation temperature from 1941. It is not THC’s boiling point at atmospheric pressure — and exactly what should replace it is still unsettled.

Cannabinoid boiling points are among the most confidently repeated figures in cannabis. Most of them come from charts that never recorded the pressure they were measured at, mixed with processing temperatures that are not boiling points at all. Recent work has started to fill the gap, but it has produced estimates that need reconciling rather than a clean set of replacement numbers.

This article covers the cannabinoids. Our companion piece explains why most terpene boiling point charts are misleading.

What does a cannabinoid boiling point actually mean?

Three different things happen when you heat a cannabinoid, and most charts blur them together.

Melting is a solid becoming a liquid. Decarboxylation is a chemical reaction: THCA or CBDA loses a carbon dioxide molecule and becomes THC or CBD. It happens well below any boiling point, it depends on time as much as temperature, and what you end up with is a different compound — our guide to what heat converts and what it costs covers it in detail. Boiling occurs when a liquid’s vapour pressure reaches the surrounding pressure, so vapour bubbles can form throughout it.

Two consequences follow from that definition, and both matter here.

A boiling point is not a property of a molecule on its own. It is a property of a molecule at a stated pressure. Lower the pressure and the boiling point falls, which is the whole principle behind vacuum distillation. In formal chemistry an unqualified boiling point normally means the value at 1 atmosphere — but cannabis charts have not followed that convention reliably, so unless the pressure is stated or clearly sourced, the number is unusable.

And a compound evaporates well below its boiling point. Boiling is the temperature at which vapour forms throughout the liquid, not the temperature at which it first enters the air. This is why a vaporizer can release THC at temperatures far below any figure in the table below.

Where did the 157 °C figure for THC come from?

The most repeated cannabinoid temperature in existence traces back to 1941.

Researchers in 2025 went looking for its provenance and found it in early isolation chemistry — Adams and colleagues in 1941, then Gaoni and Mechoulam in 1964. Both reported temperatures of approximately 157 °C for distilling THC at 0.05 Torr.

That is a hard vacuum, roughly one fifteen-thousandth of atmospheric pressure. Under that vacuum, THC could be distilled at approximately 157 °C. At atmospheric pressure, it could not.

Recent measurements broadly support the old figure as a low-pressure result. In January 2026, a NIST-led team measured THC’s vapour pressure directly and found it reaching 7.833 Pa at 151 °C — about 0.059 Torr, within the same pressure range as the early distillations. The historical number was not invented. What was lost was the pressure condition attached to it.

So what is THC’s boiling point at atmospheric pressure?

Less settled than any chart implies, including the newest one.

In December 2025, a team from Colorado College and Schwazze Biosciences published normal boiling point estimates using thermal analysis: 245 ± 6 °C for THC and 378 ± 4 °C for THCV. Those figures are considerably higher than the chart values, and the THCV result in particular suggests it is far less volatile than commonly stated.

But they are estimates, and the paper says so in its title. The measurements were taken at 610–620 mmHg, below atmospheric, and corrected to 760 mmHg using the Sydney–Young equation. The THC sample was 98% pure; the THCV sample was 84% THCV and 16% CBV. The authors also report that the heat-of-vaporization part of the method produced values that were systematically low and requires further optimization, although they retained the Sydney–Young boiling-point estimates.

Meanwhile the EPA’s chemical dashboard predicts THC’s normal boiling point at 375 °C, with a probable range of 328 to 407 °C — far above the 245 °C estimate. Separate thermodynamic work published in 2025 estimated vaporization enthalpies for THC, CBD, CBG, CBC and their varin homologues by a different route again.

So the position is not that 157 °C has been replaced by 245 °C. It is that 157 °C was never an atmospheric figure, and the atmospheric value is currently the subject of methods that disagree with each other.

The duplicates in the middle column do not prove copying on their own — structurally related compounds can have genuinely similar boiling points, and THC and CBD are outright isomers. But repeated exact matches combined with missing sources should make the whole table suspect.

Why do the acid forms show such low temperatures?

The figures given for THCA and CBDA are not boiling points at all.

THCA does not boil at 120 °C. Held near that temperature for long enough it converts into THC. What you have afterwards is a different molecule that has not vaporized yet. Decarboxylation has no single temperature either — it depends on how long the material is held as well as how hot it gets.

Putting a processing temperature in a boiling-point column is a category error. It creates the misleading impression that the acid forms are unusually volatile, when in practice they generally decarboxylate or decompose before a clean boiling point can be established.

What about cannabinoid melting points?

Melting point is a different measurement, and often the one people actually want.

Published phase-transition values put CBD near 68 °C, CBN near 79 °C and THC near 8 °C. CBD’s relatively high value helps explain why isolate is a white crystalline powder. THCA likewise readily forms visible crystals, while THC is a thick resinous oil at room temperature.

Melting only means that a solid has become a liquid. It says nothing about whether the compound is evaporating, and it does not mean that boiling has begun. If you are looking a melting point up to set a vaporizer, it is the wrong number.

Does any of this change how you should vaporize?

Corrected estimates change practice less than you might expect, and this is where the charts do the most quiet damage.

The appeal of a cannabinoid temperature chart is the idea that you can dial a device to a number and release one compound. In reality, vaporizers do not hold plant material at a uniform temperature, cannabinoids in flower are not pure isolated liquids, and they sit in a resin matrix alongside terpenes with genuinely different volatilities. What comes off is a mixture whose proportions shift with temperature, rather than compounds switching on at thresholds.

Evaporation below the boiling point is the key. The NIST measurements show THC producing measurable vapour pressure across 91 to 151 °C — well below any proposed boiling point. A vaporizer at 190 °C is not boiling THC. It is driving vapour off a complex mixture, which is what you would expect and what the threshold model fails to describe.

In practice, what matters is the balance between release and loss. Terpenes leave early and continuously, a subject we cover in what is lost after harvest, while cannabinoids degrade under sustained heat. The useful picture is a window with incomplete decarboxylation and inefficient release at the bottom and destruction at the top, not a ladder.

What should you take from a cannabinoid temperature chart?

Treat any cannabinoid boiling point without a stated pressure as unusable, because that is what it is.

The data is thin for real reasons. Cannabinoids are viscous, thermally fragile and degrade near the temperatures where they vaporize, and legal restrictions kept them out of physical chemistry labs for decades. The certified THC reference standard still ships with no data available in the boiling point field. Cannabis has more than a hundred known cannabinoids, and almost none have been studied this way at all.

That vacuum is what the charts filled. An unreferenced number that looks authoritative will circulate indefinitely, and repetition is not evidence.

What has genuinely changed is that three cannabinoids now have directly measured vapour pressures, and two have published normal boiling point estimates. That is real progress, and it is not the same as a finished chart. Replacing one deceptively precise table with another would repeat the mistake this article is about.

For the same problem in the aromatic compounds, see terpene boiling points; for how the two compound classes differ, start with cannabinoids and terpenes.

References

1. Turovsky EH, Moriarty K, Chavarria N, Parco JE, Kachadourian R, Brasuel MG. Application of thermogravimetric analysis (TGA) and differential scanning calorimetry (DSC) to estimate the normal boiling points of ∆9-tetrahydrocannabivarin (THCV) and ∆9-tetrahydrocannabinol (THC). Journal of Cannabis Research. 2026;8:9. doi:10.1186/s42238-025-00373-w
2. Beuning CN, Berry JL, Paulechka E, Huber ML, Jeerage KM, Widegren JA, Lovestead TM. Vapor pressure measurements on Δ9-tetrahydrocannabinol, cannabidiol, and cannabinol to inform cannabis breathalyzer development. Journal of Breath Research. 2026;20(1):016010. doi:10.1088/1752-7163/ae3794
3. Chickos JS. A series of cannabinoids including, cannabidiol, cannabigerol, cannabichromene, and Δ8- and Δ9-tetrahydrocannabinol are estimated using synthetic and retrosynthetic analysis, group additivity, and experiment. Structural Chemistry. 2026;37(3):1097-1108. doi:10.1007/s11224-025-02545-z
4. Adams R, Cain CK, McPhee WD, Wearn RB. Structure of cannabidiol. XII. Isomerization to tetrahydrocannabinols. Journal of the American Chemical Society. 1941;63(8):2209-2213. doi:10.1021/ja01853a052
5. Gaoni Y, Mechoulam R. Isolation, structure, and partial synthesis of an active constituent of hashish. Journal of the American Chemical Society. 1964;86(8):1646-1647. doi:10.1021/ja01062a046

Originally published January 24, 2023. Updated August 14, 2026 to correct the definition of a cannabinoid boiling point, replace figures that were vacuum distillation temperatures or processing temperatures, and add the 2025 and 2026 measurement work on THC, THCV, CBD and CBN.

Reviewed by Nani Frenkel.