E Series Preferred Numbers — Engineering Tools

🔢 E Series Preferred Numbers

IEC 60063 standard values for resistors, capacitors, and inductors. Click any value to copy it.

Find Nearest Standard Value

Target value

Series

Ratio Solver

Find the best pair of E-series resistors to achieve a target ratio R₁/R₂. Any decade scaling gives the same ratio — values are shown with R₂ ≈ 10 kΩ.

Target ratio (R₁ / R₂)

Series

Series Values

Decade

Series Overview

Series	Values/decade	Step ratio	Tolerance	Typical use
E6	6	×10^(1/6) ≈ ×1.468	±20%	General capacitors, rough value selection
E12	12	×10^(1/12) ≈ ×1.211	±10%	General resistors & capacitors
E24	24	×10^(1/24) ≈ ×1.100	±5%	Standard resistors — most common
E48	48	×10^(1/48) ≈ ×1.049	±2%	Precision resistors
E96	96	×10^(1/96) ≈ ×1.024	±1%	Precision resistors (1% — very common)
E192	192	×10^(1/192) ≈ ×1.012	±0.5%	High-precision / low-tolerance resistors

💡 The E series are defined so that each value is a rounded power of 10^(1/N), meaning the tolerance bands of adjacent values just touch — maximally efficient coverage with no gaps.