About

Electronics manufacturing relies on a standardized color-coding system defined by IEC 60062 to mark resistance values on small components where printed text is impractical. For electrical engineers, PCB designers, and hobbyists, interpreting these colored bands accurately is a fundamental necessity. A misread band can lead to circuit failure, thermal overload, or unstable signal processing. While memorizing the mnemonic "Black 0, Brown 1, Red 2..." is common, manual decoding is prone to error, especially with 5 or 6-band precision resistors involving temperature coefficients.

This tool provides a rigorous digital interface for decoding resistor bands into ohmic values and tolerances. Conversely, it offers a reverse-lookup utility, translating a desired resistance value into the necessary color sequence. It accounts for all standard variations, including 3-band legacy resistors and modern 6-band high-precision components, ensuring compliance with industry standards for component selection and verification.

Formulas

The calculation of resistance R depends on the number of bands. The logic concatenates the significant digits and applies the multiplier m.

For 4-Band Resistors:

R = (10⋅d₁ + d₂ × 10^m

For 5 and 6-Band Resistors:

R = (100⋅d₁ + 10⋅d₂ + d₃ × 10^m

Where d_n represents the digit associated with the color in the n-th position, and m is the power of 10 represented by the multiplier band. The 6th band, if present, indicates the Temperature Coefficient of Resistance (TCR), measured in ppm/K.

Reference Data

Color	Significant Digit	Multiplier	Tolerance	Temp. Coefficient
Black	0	1 Ω	-	250 ppm/K
Brown	1	10 Ω	±1%	100 ppm/K
Red	2	100 Ω	±2%	50 ppm/K
Orange	3	1 kΩ	-	15 ppm/K
Yellow	4	10 kΩ	-	25 ppm/K
Green	5	100 kΩ	±0.5%	20 ppm/K
Blue	6	1 MΩ	±0.25%	10 ppm/K
Violet	7	10 MΩ	±0.1%	5 ppm/K
Gray	8	100 MΩ	±0.05%	1 ppm/K
White	9	1 GΩ	-	-
Gold	-	0.1 Ω	±5%	-
Silver	-	0.01 Ω	±10%	-

Frequently Asked Questions

A 4-band resistor uses two bands for significant digits, one for the multiplier, and one for tolerance. It typically has a lower precision (±5% or ±10%). A 5-band resistor adds a third significant digit band, allowing for higher precision values (e.g., 125 Ohms vs 120 Ohms) and tighter tolerances (±1% or less).

There is usually a larger gap between the multiplier band and the tolerance band. The tolerance band (often Gold or Silver) is typically placed at the far right. If the bands are equally spaced, check if the first band is a color that cannot be a digit (like Gold or Silver, though rare in first position). The standard dictates reading from left to right.

The 6th band represents the Temperature Coefficient (Temp Co), which indicates how much the resistance value changes with temperature. It is measured in parts per million per Kelvin (ppm/K). This is critical for high-precision circuits exposed to varying thermal environments.

Calculated values like 453 Ohms might not exist in standard series (E12, E24). Manufacturers produce resistors in logarithmic steps. If your calculation is unique, you may need to use the closest E-series value (e.g., 470 Ohms) or use a variable resistor (potentiometer).

No. The color code strictly defines resistance, tolerance, and temperature coefficient. The power rating (Wattage) is determined by the physical size and composition of the resistor body, not the paint.