Understanding the Total THC Calculation: Decarboxylation and Its Impact

Delve into the role of decarboxylation in calculating total THC in cannabis products with Abraxas Labs. Understand the chemistry behind THC potency, consistency, and its importance for regulatory compliance in the cannabis industry.

As the cannabis industry continues to evolve, an understanding of the chemistry behind this incredible plant is becoming increasingly essential for cultivators and processors. One critical aspect of this chemistry lies in the process of decarboxylation and its impact on total THC calculations. In this post, we delve into the formula used to calculate total THC, taking into account decarboxylation during heating, and why it's crucial for your operations.

Decarboxylation: What Is It?

Before we explore the formula, let's briefly discuss decarboxylation. This process involves the removal of a carboxyl group from a molecule, and release of carbon dioxide (CO2) [1]. In the context of cannabis, decarboxylation converts the non-psychoactive THC-A (tetrahydrocannabinolic acid) into the psychoactive THC (delta-9-tetrahydrocannabinol) [2]

Cannabis plants naturally produce THCA, which, when heated (smoked, vaporized, or cooked), decarboxylates to THC, contributing to the 'high' effect. Understanding this process is crucial for cultivators and processors because it directly impacts the potency, or the subjective psychoactive effects of efficacy of cannabis products.

Calculating Total THC: The Formula

The standard formula used to calculate total THC in a sample accounting for decarboxylation is:

Total THC = (%THCA * 0.877) + %THC


This formula accounts for the molecular weight difference between THCA and THC. The 0.877 factor is the molecular weight ratio of THC to THCA (314.46 g/mol / 358.48 g/mol) [2]. This ratio reflects the fact that, during decarboxylation, THCA loses about 12.3% of its weight as it converts to THC, hence the multiplication of the THCA content by 0.877.

Why This Matters

The use of the total THC formula is important for several reasons:

  • A Way to Relay Product Potency: It provides an estimation of the potential maximum THC content in your products, as such content relates to the psychoactive and medicinal properties of THC [3]. This knowledge is essential for determining dosages, labeling, and compliance with local laws and regulations.

  • Consistency: Having a quantitative way of comparing across different genetics enables you to deliver a consistent product. Your customers need to know they're getting the same potency and effects every time they choose your products.

  • Regulatory Compliance: Many jurisdictions use total THC to determine the legality of cannabis products (e.g. differentiating hemp from cannabis). By accurately calculating total THC, you can ensure your products meet the regulatory standards and avoid legal complications.


Understanding the chemistry of cannabis, specifically the process of decarboxylation, is integral to producing quality, consistent, and legally compliant cannabis products. The total THC formula provides a simple tool for cultivators and processors to calculate the maximum THC content in their products, taking into account the crucial process of decarboxylation.

As always, Abraxas Labs is here to provide support and accurate testing for your cannabis products. We strive to ensure you have the knowledge and tools to deliver the best to your customers. For any questions or testing needs, please reach out to us.




  1. Russo, E. B. (2011). Taming THC: potential cannabis synergy and phytocannabinoid-terpenoid entourage effects. British Journal of Pharmacology, 163(7), 1344–1364. https://doi.org/10.1111/j.1476-5381.2011.01238.x
  2. Tagen, M., & Klumpers, L. E. (2022). Review of delta-8-tetrahydrocannabinol (Δ8-THC): Comparative pharmacology with Δ9-THC. British Journal of Pharmacology, 179( 15), 3915– 3933. https://doi.org/10.1111/bph.15865
  3. Hazekamp, A., & Fischedick, J. T. (2012). Cannabis - from cultivar to chemovar. Drug Testing and Analysis, 4(7-8), 660–667. https://doi.org/10.1002/dta.407
  4. Cannabis Drug Development and the Controlled Substances Act Notes 18 Duke Journal of Constitutional Law and Public Policy Sidebar 2022-2023. (2023).