THCa Decarboxylation PSI Calculator v1.3b

This calculator estimates the pressure build-up (PSI) during the decarboxylation of THCa in a closed vessel.



Ever wondered how much pressure builds up in a closed vessel during the decarboxylation of THCa? This calculator helps you estimate that pressure based on the weight of your material, its THCa concentration, and the temperature at which you are decarboxylating.

To use this calculator:

  1. Enter the input weight of your material in grams.
  2. Enter the THCa concentration as a percentage.
  3. Enter the temperature in degrees Fahrenheit at which you are decarboxylating.
  4. [Optional] Enter a custom volume of your closed vessel in fluid ounces to be shown in the first column of the chart.
  5. Click the "Calculate" button to generate the pressure heatmap.

The results are based on the ideal gas law and the stoichiometric ratios of the decarboxylation reaction.

Note: This calculator assumes the volume of approximate available headspace in your closed vessel. All of the headspace volumes are listed in parentheses (mL values).


The pressure (PSI) is estimated using the following formulas:

The underlying math is based on the ideal gas law and the stoichiometric ratios of the decarboxylation reaction. The ideal gas law is given by:

PV = nRT

Where:

  • P is the pressure in atmospheres (atm)
  • V is the volume of the vessel in liters (L)
  • n is the number of moles of gas
  • R is the ideal gas constant (0.0821 L·atm/(mol·K))
  • T is the temperature in Kelvin (K)

The decarboxylation reaction can be represented as:

1 mol THCa → 1 mol THC + 1 mol CO2

Using the molecular weights of THCa (358.48 g/mol) and CO2 (44.01 g/mol), we can determine the number of moles of CO2 produced:

n = (Input weight * THCa concentration / 100) ÷ 358.48 × 1

Finally, using the ideal gas law, we can calculate the pressure:

P = nRT ÷ V

By measuring the input parameters, we can estimate the pressure build-up during the decarboxylation process.