unitsystem

A unitsystem is a defined set of units and rules used to measure and express physical quantities. It establishes the base quantities to be measured, the base units that represent them, and the derived units and conversion factors needed to relate different measurements. The primary goal is consistency, allowing calculations, comparisons, and communication to be unambiguous across experiments, engineering, and data analysis.

The International System of Units (SI) is the most widely adopted unitsystem. SI is built on seven base units: metre for length, kilogram for mass, second for time, ampere for electric current, kelvin for thermodynamic temperature, mole for amount of substance, and candela for luminous intensity. From these base units, a broad family of derived units emerges, such as the newton (force), joule (energy), and watt (power). SI also uses prefixes (nano, micro, milli, kilo, mega, etc.) to express multiples and submultiples of units, enabling convenient handling of very large or small quantities.

Unit systems can be coherent or non-coherent. In a coherent system, derived units are formed directly from base units without additional conversion factors in equations. SI is coherent for many physical formulas, though some domains historically use alternate systems (for example, CGS, Gaussian units in electromagnetism, or imperial units). Other unit systems include metric variants, natural units used in physics to simplify equations by setting fundamental constants to unity, and practical systems tied to regional standards.

In practice, the choice of unitsystem affects clarity, compatibility with literature and equipment, and the ease of computation and data exchange. In software and data workflows, a unitsystem configuration enables automatic unit conversions, checks, and consistent representation of quantities.