Convert Kilogram (kg) to Dalton (Da) instantly.
About these units
Kilogram (kg)
The kilogram is the base unit of mass in the SI system and the only SI unit defined directly by a fundamental constant rather than a physical object. Originally, its definition was tied to a platinum–iridium artifact stored in France—the famous "International Prototype Kilogram." Over time, tiny mass changes in the prototype and its official copies created difficulties for high-precision science. In 2019, the kilogram was redefined using Planck's constant, linking mass to the laws of quantum physics through the Kibble balance. This innovation ensures universality, stability, and reproducibility across the world. The kilogram is central to commerce, science, engineering, and every quantitative field dealing with matter. Its decimal relationships with other metric units (grams, milligrams, tons) make it universally convenient. From groceries to spacecraft mass budgets, the kilogram anchors modern mass 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.