Resistor color bands

The colored bands on resistors indicate their electrical value in a globally standardized way.

About this subject

Resistors are passive electronic components that limit current in circuits. To identify their resistance value, tolerance, and sometimes temperature coefficient, a color band code is painted around the resistor body. This system was developed in the early 20th century by the Radio Manufacturers Association (RMA) and later standardized by the International Electrotechnical Commission (IEC) under IEC 60062. The coding allows even very small components to have readable specifications without additional equipment.

The code uses 4 to 6 colored bands. The first two or three bands represent significant digits, the next band is the multiplier (power of 10), and the last indicates tolerance (precision). For example, a resistor with brown, black, red, and gold bands has a value of 1,000 ohms (1 kΩ) with 5% tolerance. Each color corresponds to a number from 0 to 9: black (0), brown (1), red (2), orange (3), yellow (4), green (5), blue (6), violet (7), gray (8), and white (9). The multiplier follows the same logic, with additional colors for high values, such as silver (×0.01) and gold (×0.1).

In Brazil, the color code is taught in technical electronics courses and is fundamental for professionals. Mnemonic phrases help memorize the sequence, such as "Preto Marrom Vermelho Alaranjado Amarelo Verde Azul Violeta Cinza Branco" (the colors in Portuguese). Surface-mount resistors (SMD) use direct numbering, but the color band code remains predominant for through-hole resistors, common in prototypes and educational projects.

Interesting fact: gold (5%) and silver (10%) tolerances are the most common, but additional bands for temperature coefficient appear in precision resistors, typically blue or red. The color code is also used for capacitors, inductors, and even cables, with variations. Mastering this reading is essential for anyone involved in electronics, from hobbyists to engineers.

Frequently Asked Questions

How to read a 4-band resistor?

The first two bands are digits, the third is the multiplier (number of zeros), and the fourth is tolerance. For example, brown (1), black (0), red (×100) = 1000 ohms, with gold band (5% tolerance).

What is the color order in resistor code?

The sequence is: black (0), brown (1), red (2), orange (3), yellow (4), green (5), blue (6), violet (7), gray (8), white (9). For multipliers, silver (×0.01) and gold (×0.1) are also used.

Do SMD resistors use the same color code?

No. SMD resistors typically use 3- or 4-digit numbering without bands. For example, 102 means 1000 ohms (10 followed by two zeros). The color band code is typical for through-hole resistors.