Resistor color bands

The resistor color code is a standardized system used to identify the nominal value and tolerance of axial electronic components.

About this subject

Resistors are fundamental passive components in electronic circuits, and their resistance value is commonly indicated by colored bands. This color code was developed by the Electronic Industries Alliance (EIA) in the 1920s and is globally adopted. Each color represents a digit (black=0, brown=1, red=2, etc.), and the band sequence allows reading the value, multiplier, and tolerance. For example, a resistor with brown, black, red, gold bands equals 10 × 10² = 1000 Ω (1 kΩ) with ±5% tolerance.

Variations exist: 3-band resistors (2 digits + multiplier), 4-band (value, multiplier, tolerance), and 5 or 6 bands for higher precision or temperature coefficient. The tolerance band is typically gold (±5%), silver (±10%), or brown (±1%). This system is crucial for manufacturers, technicians, and hobbyists, enabling rapid component identification without measuring equipment.

In English-speaking countries, the color code is taught in electronics courses and vocational training. Standardization prevents assembly errors and simplifies part replacement. Despite the rise of digital printing on SMD resistors, through-hole resistors still rely on this traditional code, widely found in labs and prototyping kits.

A curiosity: the color sequence can be memorized with mnemonics like "Big Brown Rabbits Often Yield Great Big Vocal Groans When Gingerly Slapped" (though some are considered offensive). The system has been updated over the years but remains essential today.

Frequently Asked Questions

How to read a 4-band resistor?

Read the first three bands: the first two are digits and the third is the multiplier. The fourth band is tolerance. For example, brown, black, red, gold means 1, 0, multiplier 10² (100), giving 1000 Ω (1 kΩ) with ±5% tolerance.

What is the color order for resistors?

The standard order from 0 to 9 is: Black (0), Brown (1), Red (2), Orange (3), Yellow (4), Green (5), Blue (6), Violet (7), Gray (8), White (9). Gold and silver are used only as multipliers (×0.1, ×0.01) or tolerance.

What is the difference between 3, 4, and 5 band resistors?

3-band resistors have 2 digits + multiplier, no explicit tolerance (usually ±20%). 4-band resistors add tolerance. 5-band resistors have 3 digits for higher precision, and 6-band resistors also include temperature coefficient.