Convert Atomic Mass Unit (u) to Dalton (Da) instantly.
About these units
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.
Dalton (Da)
The Dalton is numerically identical to 1 atomic mass unit and is commonly used in biochemistry and molecular biology, especially for expressing the masses of proteins, peptides, and macromolecules. While "u" is often preferred in physics and chemistry, the Dalton became the standard in biological sciences because it fits neatly into descriptions of amino acids, nucleotides, and biomolecular complexes. For example, a typical protein may have a mass of 50 kilodaltons (kDa). The adoption of the Dalton helped unify communication across genomics, proteomics, and structural biology. As molecular biology expands into nanotechnology and synthetic biology, the Dalton remains a central unit for describing the building blocks of life.