Standardisarja

Standardisarja is a Finnish term used for a set of preferred numbers used as standard values in engineering, manufacturing, and measurement. These series are designed to cover a wide range of magnitudes with a small, fixed number of values per decade, enabling easy selection, interchangeability, and streamlined stocking of components and parts.

Historically these values are known as the Renard series and have been standardized internationally as the E-series in IEC standards, notably IEC 60063. Common series include E3, E6, E12, E24, E48, E96 and E192, each providing a different density of values per decade. Each series contains values between 1 and 10 that, when scaled by powers of ten, cover a broad range of sizes or values.

The values within a decade are chosen so that adjacent numbers are spaced by roughly a constant ratio. For example, the E12 series includes the values 1.0, 1.2, 1.5, 1.8, 2.2, 2.7, 3.3, 3.9, 4.7, 5.6, 6.8, and 8.2, scaled by 10^n. Components such as resistors and capacitors, as well as some mechanical dimensions, are manufactured in these standard values, often with tolerances that reflect their series.

Standardisarjat simplify design and procurement by limiting the number of distinct nominal values while still enabling close approximations to target specifications. They are widely used in electronics and related fields to support consistency and interchangeability.