Resistors, capacitors, and inductors are manufactured in standardised value sets called E-series, defined by IEC 60063. Rather than covering every decimal value, the series places values at logarithmically equal intervals so that any calculated value falls within a specified tolerance of the nearest standard value.

Logarithmic Spacing

An E-series with N values per decade places mantissas at:

The ratio between consecutive values is always 10^(1/N). This means worst-case error is at most half that ratio, or approximately 1/(2N) × 100% of a decade — which corresponds directly to the component tolerance.

Series Summary

Series	Values/decade	Tolerance	Typical use
E6	6	±20%	General decoupling capacitors
E12	12	±10%	General-purpose resistors
E24	24	±5%	Most common resistor series
E48	48	±2%	Precision resistors
E96	96	±1%	Precision resistors, filter components
E192	192	±0.5%	High-precision networks

E6 and E12 Values (first decade)

E6 mantissas: 1.0, 1.5, 2.2, 3.3, 4.7, 6.8

E12 mantissas (includes all E6): 1.0, 1.2, 1.5, 1.8, 2.2, 2.7, 3.3, 3.9, 4.7, 5.6, 6.8, 8.2

E24 adds further interleaving: 1.0, 1.1, 1.2, 1.3, 1.5, 1.6, 1.8, 2.0, 2.2, 2.4, 2.7, 3.0, 3.3, 3.6, 3.9, 4.3, 4.7, 5.1, 5.6, 6.2, 6.8, 7.5, 8.2, 9.1

Reading E-Series Values

Multiply any mantissa by a decade: a resistor marked 4.7 kΩ uses mantissa 4.7 in the kΩ decade. A capacitor of 22 nF uses mantissa 2.2 in the 10 nF decade. The E-series is the same for resistors, capacitors, and inductors — only the unit decade changes.

Choosing a Series

• E12: adequate for bias resistors, pull-ups, and non-critical dividers
• E24: standard choice for RF filter component selection
• E96 / E192: use when the component value directly sets a frequency, gain, or impedance with <1% accuracy requirement
• Higher-N series cost more and have longer lead times — use only where the tolerance budget demands it

Finding the Nearest Value

To find the nearest E-series value to a calculated target R_target: (1) compute the decade exponent exp = floor(log₁₀(R_target)), (2) extract the mantissa m = R_target / 10^exp, (3) scan all N mantissas and pick the closest. The E-Series Finder calculator automates this for any R, C, or L target.