Does THC Percentage Matter? What the Research Suggests

Stand near the counter at a licensed dispensary in New York for ten minutes and you will hear the same question over and over. What is the highest THC you have? It is an easy number to compare, it is printed in bold on every package, and it has quietly become the default shorthand for quality.

Research from the past several years suggests that shorthand is weaker than most shoppers assume, and it falls short in two separate ways. Potency tracks the felt experience less closely than the number implies, and the number itself is not always accurate. Here is what the studies indicate, what New York's own testing rules require, and what is worth reading on the label instead.

Higher THC Did Not Mean More Impairment

The most direct test of the potency assumption came from a University of Colorado Boulder team publishing in JAMA Psychiatry in 2020.^[1] Researchers studied 121 regular cannabis users in a mobile laboratory, assessing them before use, immediately after, and one hour later. Flower users were randomly assigned to 16% or 24% THC flower. Concentrate users were randomly assigned to 70% or 90% THC concentrate. All of it was purchased from licensed dispensaries rather than supplied by the researchers.

The blood work diverged sharply, exactly as you would expect. After use, concentrate users averaged 0.32 micrograms per milliliter of plasma THC. Flower users averaged 0.14, roughly half.

Then came the part that surprised the investigators. The behavioral results did not follow the blood levels. Delayed verbal memory and balance were measurably impaired after use across the whole sample, but the study reported that differing outcomes for product type, or for potency within product type, were not observed. Someone who had just used 90% concentrate did not test as more impaired than someone who had used 16% flower.

That finding deserves careful handling. This was a single cohort study of experienced users, and the authors were explicit that higher THC exposure may still carry greater risk. It is not evidence that potency is meaningless. What it suggests is narrower: the percentage on the package is a poor proxy for how a session will actually land.

Tolerance and self titration are the leading explanations. Research suggests experienced consumers adjust intake based on the effect they feel rather than consuming a fixed amount regardless of strength. The stronger product gets used in smaller quantities, which compresses much of the difference the label promises.

The Number Is Not Always the Number

The second problem is accuracy, and here the findings are harder to wave away.

A 2023 analysis published in PLOS ONE tested 23 flower samples bought from ten dispensaries along the Colorado Front Range and compared laboratory results against what the packaging claimed.^[2] Average observed potency came in at 14.98%, which the authors noted was substantially lower than the figures dispensaries typically report. On average, observed potency ran 23.1% below the lowest label value and 35.6% below the highest. Roughly 70% of samples measured more than 15% under the printed number, and three samples contained about half the maximum potency claimed.

A larger study published in Scientific Reports in 2025 looked at 277 products, 178 flower and 99 concentrate, purchased from 52 Colorado dispensaries.^[3] Using a 15% accuracy threshold, 96.0% of concentrate products matched their labels. Only 56.7% of flower products did. Both categories skewed the same direction, with observed THC lower than labeled.

The authors of both papers point to a similar mix of causes: inconsistent testing protocols between laboratories, limited regulatory oversight, and a straightforward commercial incentive, since potency figures drive shelf price. None of this is evidence of wrongdoing by any particular producer, and both studies examined the Colorado market rather than New York's. What the pattern does suggest is that the printed figure carries less information than the confidence placed in it.

What New York Actually Requires

New York's testing rules are worth knowing, because the tolerance is tighter than the threshold those studies used to judge accuracy.

Under the Office of Cannabis Management testing limits, adult use cannabis products carry a labeled potency variance of 90 to 110%.^[4] Medical cannabis products carry a wider band of 85 to 115%. The Colorado research applied a 15% threshold, so New York's adult use requirement sits inside it. Every lot must be tested by an independent laboratory permitted by the state, total THC is calculated as THCA multiplied by 0.877 plus THC, and flower results are corrected for moisture and reported on a dry weight basis.

Terpene testing is mandatory too. All cannabis products sold in New York must be tested for terpene content, against a minimum panel that includes beta-myrcene, beta-caryophyllene, limonene, alpha-pinene, alpha-humulene, linalool, beta-pinene, terpinolene and ocimene, among others. Inhalable products are capped at 10% total terpenes with a 15% variance allowed.

That requirement matters more than it sounds. It means the more informative half of the panel is already printed on the package, sitting right next to the number that gets read first.

What to Read Instead

The terpene profile

Dominant terpenes shape aroma and character, and they vary enormously between cultivars that may sit within a point or two of each other on THC. Research into how terpenes and cannabinoids interact, often discussed as the entourage effect, is ongoing and should not be treated as settled science. Even so, a profile tells you something specific about what is in the jar, where a single potency figure does not. Recent work profiling cannabis chemistry in depth found the aromatic picture is far wider than any label reports.

The rest of the cannabinoid line

CBG, CBN and CBC appear on New York panels alongside THC and CBD. The 2025 labeling study noted in passing that CBG was more abundant than CBD in both the flower and concentrate products tested, and that CBG is not currently required in potency labeling in every market. Minor cannabinoids are an active research area rather than a solved one, but they are part of what distinguishes two jars with similar THC.

Freshness

Terpenes are volatile, which means they degrade with time, light and heat in a way the THC figure does not capture. A product that tested beautifully months ago may present very differently now, which is why how flower is stored can matter as much as how it scored.

A Better Question at the Counter

Swapping one question for another costs nothing. Instead of asking which jar carries the highest number, ask what a strain smells like, which terpenes lead its profile, and how recently it was packaged. Those answers describe the product you are actually going to open.

Greenline's strains list dominant terpenes and effect notes alongside the THC figure for exactly this reason, so the profile is available before you buy rather than after you have already anchored on a percentage.

None of this argues that potency is irrelevant. It argues for demoting it from the only question to one input among several, which is closer to what the current evidence supports.

References

1. Bidwell LC, Ellingson JM, Karoly HC, et al. Association of naturalistic administration of cannabis flower and concentrates with intoxication and impairment. JAMA Psychiatry. 2020;77(8):787-796. jamanetwork.com
2. Schwabe AL, Johnson V, Harrelson J, McGlaughlin ME. Uncomfortably high: testing reveals inflated THC potency on retail Cannabis labels. PLOS ONE. 2023;18(4):e0282396. doi:10.1371/journal.pone.0282396
3. Giordano G, Brook CP, Ortiz Torres M, et al. Accuracy of labeled THC potency across flower and concentrate cannabis products. Scientific Reports. 2025;15:20822. doi:10.1038/s41598-025-03854-3
4. New York State Office of Cannabis Management. Cannabis Testing Limits, revision February 9, 2026. cannabis.ny.gov