Inductor Color Code

Decode 4-band inductors.

Band 1 Black Brown Red Orange Yellow Green Blue Violet Grey White

Band 2 Black Brown Red Orange Yellow Green Blue Violet Grey White

Multiplier Silver Gold Black Brown Red Orange

Tolerance Black (20%) Silver (10%) Gold (5%)

Inductance -- µH

Tolerance -- %

What is an Inductor Color Code?

Just like resistors, small axial inductors use a standard Inductor Color Code (EIA-RS-279) to indicate their inductance and tolerance values. Because these components are often too small to print text on, colored bands corresponding to numbers are painted on the body.

The system is nearly identical to the resistor color code, but with one critical difference: the base unit is Microhenries (µH), whereas resistors are in Ohms. Being able to decode these bands instantly is vital for repairing vintage electronics or verifying component values in RF circuits.

How to Read the Code (The Formula)

Most color-coded inductors use a 4-band system. The reading direction is usually indicated by a wider silver or gold band at one end (tolerance) or by starting from the band closest to a lead wire.

Band Breakdown

• Band 1 (First Digit): Represents the first significant figure (e.g., Brown = 1).
• Band 2 (Second Digit): Represents the second significant figure (e.g., Black = 0).
• Band 3 (Multiplier): The power of 10 to multiply by.
  • Gold = ×0.1 (Decimal point shift)
  • Silver = ×0.01
  • Black = ×1, Brown = ×10, etc.
• Band 4 (Tolerance): How accurate the value is (Gold = ±5%, Silver = ±10%, Black = ±20%).

Practical Applications

Inductors are key components in analog electronics:

• RF Circuits: Used in LC tank circuits to tune radios to specific frequencies.
• Power Supplies: "Chokes" block high-frequency AC noise while letting DC flow through, smoothing out power rails.
• Audio Filters: Used in crossover networks to direct bass frequencies to woofers and block trebles.

FAQ