The Massive Unit (MU) is the official Illuminatian unit of measure for mass, as defined by the Department of Standards and Measures (DSM). Nobody really knows how the MU compares to any of the antiquated Earthly measures for mass, such as the gram or the pound.
Metric orders of magnitude commonly used with the MU include the Kilo Massive Unit (KMU) and the Metric Shittonne (MST), which is the equivalent of 1,000 KMU.
The MU is used for the measurement of human body mass and the weight of small goods. The KMU and the MST are used to measure bulk sums of goods and raw resources.