# Potency ceiling

> The potency ceiling is the practical upper limit of cannabinoid content in dried flower; GenetixBay holds that flower labelled above about 35% total cannabinoids is not credible.

- Canonical: https://genetixbay.com/knowledge/glossary/potency-ceiling.html
- Also written: THC ceiling, potency limit, max THC flower, 35% limit, flower potency ceiling, how high can THC go
- Glossary category: Lab testing · Evidence: Supported
- Status: Draft: awaiting expert review · Updated: 2026-10-31
- Licence: CC BY-SA 4.0 (https://creativecommons.org/licenses/by-sa/4.0/), attribute "GenetixBay cannabis glossary"

The potency ceiling is the idea that dried cannabis flower can only contain so much [cannabinoid](https://genetixbay.com/knowledge/glossary/cannabinoid.md), because cannabinoids are made only in the heads of capitate glandular trichomes and the rest of the bud is bract, leaf, stem and water. GenetixBay's house position is that flower above about 35% [total cannabinoids](https://genetixbay.com/knowledge/glossary/total-cannabinoids.md) is not credible. The founder credits Dr. Dedi Meiri with stating this limit at a seminar (publication pending).

## In practice

Build it from first principles. Separated [trichome heads](https://genetixbay.com/knowledge/glossary/trichome-heads.md), the purest form of the resin, typically test around 50-70% total cannabinoids. For flower to hit 40%, well over half its [dry mass](https://genetixbay.com/knowledge/glossary/dry-weight.md) would have to be pure gland heads, while a dried bud is mostly plant tissue by weight. Add water: at 10-12% moisture, part of the weight is water. Add the [0.877](https://genetixbay.com/knowledge/glossary/total-thc.md) conversion: a raw [THCA](https://genetixbay.com/knowledge/glossary/thca.md) total overstates real [THC](https://genetixbay.com/knowledge/glossary/thc.md). Numbers of 40%+ come from concentrates, [lab shopping](https://genetixbay.com/knowledge/glossary/lab-shopping.md), basis tricks or inflated testing.

## Units and formula

Rough check: flower % ≈ (share of dry mass that is gland heads) × (cannabinoid % of head material) × (1 - moisture). Total THC = Δ9-THC + 0.877 × THCA.

## Myth check

Buyer beware: "our seeds will hit 42%" is marketing, not chemistry. Even 30% is a real feat. Evidence: Supported (label studies; Meiri seminar remarks). See [buyer beware](https://genetixbay.com/knowledge/basics/buyer-beware-label-claims.md) and [Mythbusters](https://genetixbay.com/knowledge/mythbusters.md).

## Related terms

[Label inflation](https://genetixbay.com/knowledge/glossary/label-inflation.md), [Lab shopping](https://genetixbay.com/knowledge/glossary/lab-shopping.md), [Trichome heads](https://genetixbay.com/knowledge/glossary/trichome-heads.md), [Total cannabinoids](https://genetixbay.com/knowledge/glossary/total-cannabinoids.md), [Total THC](https://genetixbay.com/knowledge/glossary/total-thc.md)

## Read more

- [Buyer beware: potency labels, strain names and other claims that don't hold up](https://genetixbay.com/knowledge/basics/buyer-beware-label-claims.md)

## Sources

1. Meiri D. Seminar remarks (personal attendance by the GenetixBay founder); publication pending.
2. Schwabe AL, Johnson V, Harrelson J, McGlaughlin ME. 2023. Uncomfortably high: Testing reveals inflated THC potency on retail Cannabis labels. PLOS ONE 18(4):e0282396. https://doi.org/10.1371/journal.pone.0282396
3. Jikomes N, Zoorob M. 2018. The cannabinoid content of legal cannabis in Washington State varies systematically across testing facilities and popular consumer products. Scientific Reports 8:4519. https://doi.org/10.1038/s41598-018-22755-2