Electronic color code

Resistor bands encode resistance as significant digits followed by a multiplier and, usually, a tolerance. In the common four-band system, the first two bands are digits, the third is the power-of-ten multiplier, and the fourth gives tolerance; five-band resistors use three significant digits before the multiplier. The digit sequence is black 0, brown 1, red 2, orange 3, yellow 4, green 5, blue 6, violet 7, gray 8, and white 9.¹

Gold represents a multiplier of 0.1 and silver 0.01 when used in the multiplier position. In the tolerance position, gold commonly means ±5%, silver ±10%, and brown ±1%; red, green, blue, violet, and gray can represent progressively specified tolerances in precision systems. A resistor is normally read from the end where the bands are closest together, with the tolerance band separated by a larger gap.

Color markings also appeared on capacitors, inductors, diodes, and older electronic assemblies, but their conventions are not universal. Capacitor color systems may encode capacitance, voltage rating, tolerance, or temperature coefficient, while inductor markings can resemble resistor bands but use units appropriate to inductance. Printed alphanumeric codes increasingly replaced colored bands because they carry more information in less space and are easier to interpret automatically.

Component families may follow national or manufacturer-specific standards rather than one universal table. International standardization work for marking codes is associated with IEC 60062, which covers marking codes for resistors and capacitors.² Datasheets remain the controlling authority when a marking could have more than one interpretation, particularly for surface-mount parts, safety components, and molded capacitors.

Color code reading should be checked against the component’s physical form, circuit position, and measured value. A 1-kilohm resistor with 5% tolerance is commonly marked brown-black-red-gold: 10 multiplied by 100, with a ±5% tolerance. The nominal value is not an exact measurement; a compliant part may fall anywhere within its stated tolerance, and resistance can also vary with temperature, applied voltage, aging, and frequency.

Color perception creates practical edge cases. Red and brown, blue and violet, or gray and white may be confused under poor lighting, while heat, chemicals, and fading can obscure old bands. Color-vision deficiencies do not make identification impossible, because band spacing, a multimeter measurement, and the circuit’s expected value provide independent checks. Never infer a safety rating from color alone: voltage, power, insulation, and certification markings must come from the component documentation.

The code is a compact form of positional notation rather than a set of arbitrary labels: the first colors represent digits, and later colors shift the decimal scale. This makes the sequence memorable and lets a limited palette describe many values. Zero-ohm links may use a single black band or a printed marking, and some jumpers are physically resistors even though they are intended to have negligible resistance.

Color coding also reflects the history of component manufacture. Through-hole parts had enough cylindrical surface for bands, whereas modern surface-mount resistors usually carry short printed codes or no visible code at all. Axial components can additionally use a body color to identify a family or construction type, so body color must not automatically be read as a numeric band. Standardized codes improve interchangeability, but visual inspection remains a preliminary identification method rather than a substitute for a schematic, datasheet, or measurement.

Significant digit

A digit that contributes directly to a component’s stated nominal value.

Multiplier

A power-of-ten factor applied to the significant digits.

Tolerance

The permitted deviation of a component’s actual value from its nominal value.

Zero-ohm link

A component or jumper designed to connect two points with very low resistance.