EReihen

E-Reihen, or E-Series, are standardized sets of preferred numbers used to specify component values in electronics, especially resistor values. They provide a practical way to stock and select values that cover a wide range without requiring an excessive variety of discrete parts. The E-Series are defined internationally under standards such as IEC 60063.

Each series includes a fixed number of values per decade (per power of ten). Values in a decade are scaled by powers of ten, so a basic set in one decade repeats across higher or lower decades. For example, the E12 series has 12 values per decade. In the first decade the common nominal values are 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. In subsequent decades these values are multiplied by 10, 100, 0.1, etc., to yield values such as 10, 12, 15, 18, 22, 27, 33, 39, 47, 56, 68, 82 ohms, and so on.

Other well-known E-Series include E3, E6, E24, E48, E96 and E192, which offer increasingly finer granularity of values per decade. The trade-off is between precision and the variety of stock keeping units required. In practice, designers combine E-Series values with component tolerances (for example ±1%, ±2%, ±5%) to approximate target specifications.

History and standardized use: The concept of preferred numbers predated electronics, but the E-Series were formalized by international standards and have since become a foundation of component value assignment in electronic design, manufacturing, and procurement. They enable interoperability and simplify inventory management across industries.