35% THC isn’t the point: what really defines a strain

The THC percentage on a label tells you how much of one compound is in the flower, and that’s it. It doesn’t tell you how a strain smells, how it tastes or how it feels — and the number itself is often inflated. Recent research points the same way: terpenes and other aroma compounds say more about a strain’s character than chasing percentages.

In short

• Most labels show “total THC”. It’s calculated from THCA — the acid form that only turns into THC when heated.
• Independent testing finds label numbers are often inflated: in one study that was true for about 70% of samples.
• In a University of Colorado experiment, people who smoked flower with 16% and 24% THC rated how they felt almost the same.
• “Indica” and “sativa” labels match the plant’s actual chemistry poorly. Terpenes are a more reliable guide.
• The famous “gas” smell doesn’t even come from terpenes — it comes from trace sulfur compounds.

What’s really on the label: THC or THCA?

A living plant contains almost none of the THC that actually acts on you. The plant produces THCA — tetrahydrocannabinolic acid. On its own it isn’t psychoactive. For THCA to become THC, a carboxyl group has to break off the molecule, which happens with heat, when the flower is smoked or vaporized. The process is called decarboxylation.

That’s why labs usually report “total THC” and calculate it with a formula:

Total THC = THC + 0.877 × THCA

The 0.877 factor is pure chemistry: as the carboxyl group leaves, it takes about 12% of the molecule’s mass with it. One gram of THCA yields roughly 0.877 grams of THC. So “32% THC” on a jar almost always means the flower holds about 36% THCA and very little ready THC, and the final number is an estimate of what you’ll get after heating.

Can you trust that number?

Not always. In 2023, biologists from the University of Northern Colorado bought 23 samples at ten licensed dispensaries in the state and sent them for independent testing. In about 70% of samples, the real THC content was at least 15% lower than the label said. The paper was published in PLOS ONE under the telling title “Uncomfortably High”.

The reason is easy to see: for years the market taught buyers that a higher percentage means better, and a big number sells. That puts pressure on producers and labs. So treat the number on the jar as a rough guide, not a precise measurement.

Higher percentage, stronger effect?

This is where it gets interesting. In 2020, researchers at the University of Colorado Boulder published an experiment with 121 regular users in JAMA Psychiatry. Some smoked flower with 16% or 24% THC, others used concentrates with 70% or 90%. Blood THC levels were noticeably higher in the concentrate group. Yet participants rated how high they felt very similarly, and the authors put it plainly: potency did not track with level of intoxication.

Scientists are still debating why. Tolerance plays a role, as does how people dose themselves and how fast they smoke — and probably the mix of other compounds in the plant. But the practical takeaway is already clear: the difference between 24% and 30% on a label means far less than it seems.

Indica and sativa aren’t a guarantee either

In 2022, a research team analyzed about 90,000 lab tests of commercial cannabis from six US states. It turned out that the “indica”, “sativa” and “hybrid” labels matched the real chemistry poorly: products with different labels often had indistinguishable terpene profiles.

The samples themselves, though, fell neatly into three terpene groups:

• dominated by caryophyllene and limonene;
• dominated by myrcene and pinene;
• dominated by terpinolene and myrcene.

The researchers’ conclusion: a label needs an “ingredients list”, like food does, not a single word about type.

What are terpenes?

Terpenes are aromatic compounds the plant produces in the same resin glands — trichomes — as cannabinoids. They aren’t unique to cannabis: limonene is the smell of citrus peel, pinene of a pine forest, linalool of lavender. Flower usually holds only about one to three percent terpenes by weight, but they’re what make a strain recognizable.

Terpenes are very volatile. They evaporate during drying and with heat and light — which is why proper curing and storage in a closed jar matter so much, especially in hot weather.

The entourage effect: what does science know?

The idea behind the entourage effect is simple and appealing: the plant’s compounds don’t work alone but together, and terpenes change how THC feels. It was popularized by neurologist Ethan Russo in a 2011 review. Since then the hypothesis has become a favorite topic for the industry — and a subject of debate among scientists.

Here’s what’s known so far:

• Caryophyllene is a special case. In 2008, Swiss researchers showed in PNAS that beta-caryophyllene binds to the CB2 cannabinoid receptor. The authors called it a “dietary cannabinoid”: the same caryophyllene is found in black pepper and cloves.
• No effect at the receptor level. In 2019, an Australian group tested the main cannabis terpenes in cells with human CB1 and CB2 receptors. The terpenes didn’t change how THC acts on those receptors. The paper’s title says it all: “Absence of Entourage”.
• First human data are cautiously interesting. In 2024, researchers at Johns Hopkins University ran a double-blind study with 20 volunteers. When limonene vapor was added to THC, participants reported less anxiety and paranoia, while THC’s other effects stayed the same. The authors themselves call it a “first step”: the sample is small and the results need to be replicated.

The honest bottom line: terpenes definitely shape a strain’s aroma and flavor and may influence how it feels, but by how much, science is still working out. Any promise like “this terpene is for sleep, that one for energy” is ahead of the evidence for now.

Why does flower smell like “gas” if there’s no such terpene?

This stayed a mystery for a long time: the terpene profiles of many “gassy” strains are almost the same as those of sweet ones. The answer was found by chemists at the American company Abstrax.

In 2021 they described a new family of volatile sulfur compounds in the journal ACS Omega. The main one is prenylthiol (3-methyl-2-butene-1-thiol). It’s the same compound that makes beer “skunky” in sunlight, and it’s also behind cannabis’s sharp skunky smell. There’s only a trace of it, but our noses pick up sulfur compounds at tiny concentrations.

In 2023 the same team went further and analyzed 31 samples of exotic strains. They found that:

• Tropical and citrus notes come from sulfur compounds with a 3-mercaptohexyl group. Related molecules are responsible for the aroma of passion fruit and Sauvignon Blanc wine.
• Savory, “garlicky” notes in strains like GMO come from skatole and related compounds.
• Terpene profiles of strains that smell completely different turned out to be nearly identical. The authors wrote outright that the role of terpenes in cannabis aroma is “overstated”.

Our example is Gas Fanta. Its card lists valencene (sweet orange), while its name says “gas”. The orange comes from terpenes, and the gas most likely from exactly those trace sulfur compounds.

How to use this when choosing

Instead of hunting for the biggest number, look at what actually describes a strain. In the BND catalog every item lists its type, flavor, terpenes and farm:

• Remember two or three terpenes you like. If you enjoyed a strain with limonene, there’s a good chance you’ll like another with the same terpene, even under a completely different name.
• Read the flavor. “Gas”, “candy”, “cream” describe the whole bouquet, including those sulfur compounds that don’t appear in the terpene line.
• Don’t overpay for percentages. A couple of points of THC on the label mean almost nothing, while flavor and aroma you’ll notice right away.
• Pay attention to the farm. The same strain from different farms and different harvests can vary — terpenes depend on growing conditions and curing.

Terpenes and flavor are listed on every strain’s card in our catalog. Want help choosing a strain by aroma? Message us on Telegram and we’ll help.

This article is for information only and is not medical advice.

Sources

• Schwabe A. L. et al. Uncomfortably high: Testing reveals inflated THC potency on retail cannabis labels. PLOS ONE, 2023.
• Bidwell L. C. et al. Association of Naturalistic Administration of Cannabis Flower and Concentrates With Intoxication and Impairment. JAMA Psychiatry, 2020.
• Smith C. J. et al. The phytochemical diversity of commercial Cannabis in the United States. PLOS ONE, 2022.
• Russo E. B. Taming THC: potential cannabis synergy and phytocannabinoid-terpenoid entourage effects. British Journal of Pharmacology, 2011.
• Gertsch J. et al. Beta-caryophyllene is a dietary cannabinoid. PNAS, 2008.
• Santiago M. et al. Absence of Entourage: Terpenoids Commonly Found in Cannabis sativa Do Not Modulate the Functional Activity of Δ9-THC at Human CB1 and CB2 Receptors. Cannabis and Cannabinoid Research, 2019.
• Spindle T. R. et al. Vaporized D-limonene selectively mitigates the acute anxiogenic effects of Δ9-tetrahydrocannabinol in healthy adults who intermittently use cannabis. Drug and Alcohol Dependence, 2024.
• Oswald I. W. H. et al. Identification of a New Family of Prenylated Volatile Sulfur Compounds in Cannabis Revealed by Comprehensive Two-Dimensional Gas Chromatography. ACS Omega, 2021.
• Oswald I. W. H. et al. Minor, Nonterpenoid Volatile Compounds Drive the Aroma Differences of Exotic Cannabis. ACS Omega, 2023.