Mentech Magnetic Product Line

Electronic identification systems have evolved alongside component manufacturing, but understanding classic visual standards remains an essential skill for circuit design, board repair, and engineering education. Inductor color codes provide a quick visual method for determining the electrical values of traditional leaded components.

Knowing how to read standard 4-band and 5-band military color systems helps technicians and engineers verify values without relying solely on test equipment.

Scope & Physical Application of Color Codes

Color codes are primarily used on legacy through-hole components, such as axial and radial leaded inductors (often called color-ring or color-code inductors). Because these components feature cylindrical bodies with sufficient surface area, painted rings remain an economical and readable method for marking specifications.

Modern surface-mount technology (SMT)—such as SMD molded power inductors—has largely phased out painted color bands due to compact footprints, thermal molding processes, and automated SMT assembly requirements. However, color coding remains a standard foundational topic in passive component identification.

Standard Inductor Color Code Reference Chart

Inductor color coding follows standard IEC international conventions. The base unit for calculating inductance values from color bands is always the microhenry ().

The Standard Commercial 4-Band System

Most commercial axial-leaded inductors utilize a 4-band identification system. Reading starts from the band located closest to the edge of the component body.

· Band 1: First significant digit

· Band 2: Second significant digit

· Band 3: Multiplier ()

· Band 4: Tolerance percentage

Calculation Formula

Practical Examples

· Yellow – Violet – Black – Gold:

o Yellow (4), Violet (7), Black (), Gold ()

o Value:

· Brown – Black – Gold – Silver:

o Brown (1), Black (0), Gold (), Silver ()

o Value:

The Military-Spec (MIL-SPEC) 5-Band System

High-reliability and military-grade components governed by standards such as MIL-PRF-15305 employ a 5-band color system.

· Band 1 (Double-Width Band): Military identifier (MIL marker), which also indicates the starting side for reading.

· Band 2: First significant digit

· Band 3: Second significant digit

· Band 4: Multiplier

· Band 5: Tolerance

When military inductors have values under , a Gold band may serve as a decimal point () within the significant digit positions rather than purely functioning as a multiplier.

Conclusion

Understanding these visual systems ensures accurate component identification during inspection, testing, and legacy circuit maintenance.

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