Subgram

Subgram is an informal term used to describe a mass that is less than one gram. It is not an official SI unit, and its use varies by context. In scientific and everyday writing, quantities under a gram are typically expressed in milligrams, micrograms, or smaller SI prefixes, depending on the required precision. The term subgram may appear to indicate small quantities without committing to a specific unit, but precise communication usually specifies the exact unit (for example, 12 mg or 0.5 µg).

Common subdivisions of the gram below one gram include milligrams (mg), micrograms (µg), nanograms (ng), and smaller units. For reference, 1 g equals 1,000 mg, 1,000,000 µg, and 1,000,000,000 ng. The broad use of subgram covers all these units, but it does not replace them in formal contexts.

In practice, subgram quantities arise in medicine, pharmacology, chemistry, biology, and food labeling where small masses are relevant. Laboratory measurement typically relies on calibrated balances or scales capable of weighing to the milligram, microgram, or nanogram level, depending on equipment and required accuracy. Advanced techniques such as mass spectrometry or microbalances enable measurements at the microgram to nanogram scale.

Best practice in formal documentation is to specify the unit alongside the value to avoid ambiguity. For example, “0.25 mg” is clear, whereas “subgram quantity” alone may be imprecise. Subgram remains a descriptive convenience rather than a formal unit, emphasizing quantities smaller than a gram but requiring explicit units for clarity. See also Gram, Milligram, Microgram, Nanogram, and SI units.