What total means in a report
Under a common analytical convention, total THC combines delta-9-THC with the potential contribution of THCA using a mass correction. The usual formula is total THC = delta-9-THC + 0.877 × THCA, always with compatible units. NIST has used this expression in materials explaining measurement. You need to check which definition the particular report adopts. NIST: explaining total THC
The factor is not a quality score or a coefficient that predicts an experience. It reflects a molecular mass relationship when expressing the potential of the acidic form as the neutral form. The calculated figure does not necessarily describe what will happen under every real-world condition either. It is an analytical definition and should be read as such.
An example just to understand the table
Suppose a fictional sample contains 0.04% delta-9-THC and 0.10% THCA. Applying that convention gives 0.04 + 0.0877 = 0.1277%. The report will determine how to round the result and communicate uncertainty. This example represents no commercial product and does not determine its legality.
If another table shows only 0.04%, we cannot assume it contradicts the first. It may be reporting delta-9-THC alone. The conflict disappears when equivalent quantities are compared. There could also be a real difference between samples, but before investigating, you need to rule out headings with different meanings.
Dry-weight basis is another piece
A result expressed on a dry-matter basis is not necessarily equivalent to one expressed for the material as received. Moisture changes the denominator. A report should therefore clarify its reporting basis where relevant. Comparing percentages without checking this note may produce a difference that does not come from the amount of cannabinoid we imagine.
NIST developed hemp reference material RM 8210 with characterisation of cannabinoids, elements and moisture. That work illustrates why reliable measurement requires control of several related quantities. The document concerns an analytical reference; it does not make any similar-looking sample an approved product. NIST: characterisation of RM 8210
Do not turn a formula into authorisation
Definitions and thresholds depend on the rule, product type and jurisdiction. A formula used in a US context does not itself establish the Spanish framework for marketing products. Nor does it allow someone to select whichever figure appears most convenient and omit the other results.
The practical approach is to look for four things together: the name of the analyte or total, formula, units and calculation basis. Then interpret the result in its appropriate context. A certificate becomes more than a collection of percentages: it provides a coherent explanation of what was measured and how it was summarised.
Take this with you
Compare total THC with total THC and delta-9-THC with delta-9-THC, checking the formula, units and reporting basis.
Sources you can open
The source may be in its original language. English publication does not change the jurisdiction or date discussed.
Follow the thread
Open the cannabinoid encyclopedia
Check the identity, research, uncertainties and documented forms of each compound.