Convert Milligram (mg) to Atomic Mass Unit (u) instantly.
About these units
Milligram (mg)
A milligram is one-thousandth of a gram and essential for measuring extremely small masses with precision. Pharmacology relies heavily on milligrams to dose medications safely and consistently—especially potent drugs where differences of a few milligrams can be critical. In chemistry and laboratory science, milligrams are used to weigh reagents, catalysts, micro-samples, and test materials. Environmental science uses milligrams per liter or milligrams per kilogram to describe concentrations of contaminants. Its small size makes the milligram ideal for fields requiring strict quantitative control, and its stability within the metric system ensures predictable conversions during calculations.
Atomic Mass Unit (u)
The atomic mass unit (u) is defined as exactly 1/12 the mass of a neutral carbon-12 atom, which makes it approximately 1.66053906660 × 10⁻²⁷ kilograms. This definition allows scientists to express atomic and molecular masses in a convenient, intuitive scale that aligns with the structure of the periodic table. By anchoring the unit to carbon-12, chemists and physicists gained a universal reference point that harmonizes molecular weight, relative isotopic abundance, and mass spectroscopy results. The atomic mass unit effectively normalizes the complexity of atomic masses into whole-number or near-whole-number values for most nuclei. In chemistry, u is indispensable for calculating molar masses, reaction stoichiometry, and isotopic compositions. It is also used across nuclear physics, astrophysics, and biophysics, demonstrating the universality of atomic-scale measurement.