Percentages need a denominator. In plant testing, the amount of water included in the sample’s weight can change how a concentration is expressed.
The same amount, a different percentage
Consider an invented arithmetic example, unrelated to a commercial product. A sample weighs 10 grams, including 2 grams of water, and contains 1 gram of a measured constituent. That constituent represents 10% of the original weight. Relative to the remaining 8 grams after water is excluded, it represents 12.5%.
The amount of the constituent did not increase. The basis of the calculation changed. This is why a dry-weight result and an as-received result should not automatically be treated as equivalent numbers.
Moisture measurement is itself a measurement problem
In a report published April 28, 2025, NIST examined moisture results reported by participating laboratories for one hemp material. The laboratories used different drying methods and reported a wide range of moisture values. NIST identified a need for consistent drying methods to improve accuracy and precision. Source: NIST CannaQAP Exercise 3 Moisture Final Report.
This study concerns analytical comparability. It is not a household drying recommendation, and it does not establish that a particular commercial item has been handled improperly.
Ask what the number is based on
When two reports disagree, check their reporting basis before interpreting the difference as a change in composition. Useful questions include whether moisture was measured, whether results were adjusted to dry weight, and whether the methods are comparable.
An unexplained percentage can conceal more than it reveals. Stating the measurement basis helps a reader understand what was calculated before deciding what the number means.