Cannabis flower products frequently overstate THC potency on labels while concentrates are more accurate
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.
Quick Facts
What This Study 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.
Key Numbers
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 They Did This
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.
Why This Research 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 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.
What This Study Doesn't 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.
Questions This Raises
- ?What regulatory mechanisms could improve flower THC label accuracy?
- ?Are dispensaries or testing labs more responsible for inflated THC numbers?
Trust & Context
- Key Stat:
- of flower vs. concentrate products had THC content within 15% of the label, revealing a major flower labeling accuracy problem
- Evidence Grade:
- Well-designed blinded testing with products from multiple dispensaries and independent lab analysis, providing strong evidence of labeling discrepancies.
- Study Age:
- 2025 publication.
- Original Title:
- Accuracy of labeled THC potency across flower and concentrate cannabis products.
- Published In:
- Scientific reports, 15(1), 20822 (2025)
- Authors:
- Giordano, Gregory(4), Brook, Colin P, Ortiz Torres, Marco(2), MacDonald, Grace, Skrzynski, Carillon J, Lisano, Jonathon K, Mackie, Duncan I, Bidwell, L Cinnamon
- Database ID:
- RTHC-06542
Evidence Hierarchy
A snapshot of a population at one point in time.
What do these levels mean? →Frequently Asked 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.
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Cite This Study
https://rethinkthc.com/research/RTHC-06542APA
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
MLA
Giordano, Gregory, et al. "Accuracy of labeled THC potency across flower and concentrate cannabis products.." Scientific reports, 2025. https://doi.org/10.1038/s41598-025-03854-3
RethinkTHC
RethinkTHC Research Database. "Accuracy of labeled THC potency across flower and concentrat..." RTHC-06542. Retrieved from https://rethinkthc.com/research/giordano-2025-accuracy-of-labeled-thc
Access the Original Study
Study data sourced from PubMed, a service of the U.S. National Library of Medicine, National Institutes of Health.
This study breakdown was produced by the RethinkTHC research team. We analyze and report published research findings without making health recommendations. All interpretations are based solely on the published abstract and study data.