Submultiples

Submultiples are units of measurement that represent fractions of a base unit. In the International System of Units (SI), submultiples are formed by prefixes that denote powers of ten with negative exponents. Common submultiples include deci- (10^-1), centi- (10^-2), milli- (10^-3), micro- (10^-6), nano- (10^-9), pico- (10^-12), femto- (10^-15), atto- (10^-18), zepto- (10^-21), and yocto- (10^-24). These prefixes are applied to base or derived units to express smaller quantities.

Common examples illustrate the idea: a centimeter is one hundredth of a meter (0.01 m), a millisecond is one thousandth of a second (0.001 s), and a microampere is one millionth of an ampere (1 μA). Submultiples are widely used to describe measurements that are too large or too small to be convenient in base units.

Submultiples contrast with multiples, which use positive powers of ten (for example kilometer, meaning 1000 meters; megahertz, meaning 1,000,000 hertz). They form part of the broader system of prefixes that standardize how quantities are expressed across science, engineering, and everyday life. While SI prefixes are decimal, some fields and historical contexts may use non-decimal or non-SI prefixes for specialized purposes.

The choice of submultiples enables precise and consistent communication of magnitude, fosters comparability across disciplines, and supports clear reporting of measurements in tables, graphs, and technical documentation.