Cannabis flower products frequently overstate THC potency on labels while concentrates are more accurate | Research

The takeaway

Independent testing of 277 Colorado cannabis products found that only 57% of flower products had THC within 15% of the labeled amount, compared to 96% of concentrates, with both types averaging lower THC than advertised.

Cannabis consumers, regulators, dispensary operators, and testing laboratories.

What the researchers found

Labeling accuracy depended dramatically on product type: 96% of concentrates were within 15% of labeled THC versus only 56.7% of flower products. Observed THC was significantly lower than labeled THC for both flower and concentrate products. Nearly half of flower products failed the accuracy threshold.

Why it matters

If consumers cannot trust THC labels, they cannot make informed decisions about dosing, which is especially important for medical patients and those trying to manage their consumption. Flower labeling inaccuracy may also mean consumers overpay for potency they are not receiving.

The numbers in context

277 products from 52 dispensaries. Flower: 56.7% within 15% accuracy. Concentrates: 96.0% within 15% accuracy. Both had lower observed than labeled THC (p=0.001 for flower, p=0.003 for concentrates).

How the study worked

277 cannabis products (178 flower, 99 concentrates) purchased from 52 Colorado dispensaries and independently analyzed for THC content. Products classified as accurate if observed THC was within 15% of labeled value.

What this study cannot tell us

Colorado-specific findings may not generalize to other states with different testing regulations. The 15% accuracy threshold is arbitrary. Products tested at one point in time may not reflect batch-to-batch variation.

How to read the evidence

Well-designed blinded testing with products from multiple dispensaries and independent lab analysis, providing strong evidence of labeling discrepancies.

When this study was published

2025 publication.

The bigger picture

THC label inflation has been suspected in the cannabis industry, where higher-potency products command premium prices. This independent verification confirms the problem is real and concentrated in flower products, where testing and quality control may be less standardized.

Questions still open

What regulatory mechanisms could improve flower THC label accuracy?
Are dispensaries or testing labs more responsible for inflated THC numbers?

Common questions

Why are flower labels less accurate than concentrate labels?

Concentrates are more homogeneous, making testing more consistent. Flower THC content varies within a plant and between buds, so a sample tested may not represent the whole batch. There may also be less incentive or ability to inflate concentrate numbers.

Does lower-than-labeled THC mean products are less effective?

If a consumer is dosing based on the label, they may receive less THC than expected. For medical patients, this could mean inadequate symptom relief. For recreational users, it may simply mean they are paying premium prices for standard potency.

Read the original research

Accuracy of labeled THC potency across flower and concentrate cannabis products.

Scientific reports, 15(1), 20822

View on PubMed ↗Publisher’s paper ↗

Citation

Giordano, Gregory; Brook, Colin P; Ortiz Torres, Marco; MacDonald, Grace; Skrzynski, Carillon J; Lisano, Jonathon K; Mackie, Duncan I; Bidwell, L Cinnamon. (2025). Accuracy of labeled THC potency across flower and concentrate cannabis products.. Scientific reports, 15(1), 20822. https://doi.org/10.1038/s41598-025-03854-3