THCA and delta-9 THC are related compounds. THCA is the acidic form found in raw plant material; delta-9 THC is the neutral form. The difference is a carboxyl group that is removed when the acidic form is exposed to heat over time, a process called decarboxylation.
How each is measured
A laboratory measures both compounds separately in a sample. Reports usually list each cannabinoid by weight percentage, alongside a limit of quantitation for the method used.
Total THC calculations
Many reports also show a 'total THC' figure. A common industry formula is delta-9 THC plus 0.877 multiplied by THCA. That factor accounts for the mass lost when the carboxyl group is removed. Different jurisdictions and labs may present this differently.
Why retailers distinguish them
Hemp product compliance in the United States is generally assessed against delta-9 THC concentration on a dry weight basis. Rules, interpretations and enforcement vary by state and change over time, so check the laws that apply where you live.
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