Test Process that measures the conventional value of the result of weighing a body in air equals the mass of a standard that balances this body under the following conventionally chosen conditions: ambient temperature 20 °C air density 1.2 mg/cm³ mass density 8.000 g/cm³ Conventional mass has the same unit as mass (the kilogram), because the multiplication of a mass by a dimensionless quantity defines its values. Labs typically measure mass and correct the results from actual to conventional conditions. “Apparent Mass versus 8.0 g/cm³” formerly equated to conventional mass in the United States. References: NISTIR 6969 (2019) https://www.nist.gov/publications/nistir-6969-selected-laboratory-and-measurement-practices-and-procedures-support-1 OIML D28 (2004) https://www.oiml.org/en/files/pdf_d/d028-e04.pdf NIST Handbook 44: https://www.nist.gov/pml/weights-and-measures/publications/nist-handbooks/other-nist-handbooks/other-nist-handbooks-2-3