Resistor color bands

Colored bands on resistors encode resistance values and tolerance, an internationally standardized system used since the 1920s.

About this subject

Resistors are passive electronic components that limit current flow. Their resistance is indicated by colored bands, following the IEC 60062 standard. The colors represent digits 0, 9: black (0), brown (1), red (2), orange (3), yellow (4), green (5), blue (6), violet (7), gray (8), and white (9). The number of bands varies: 4-band resistors are most common, with two digit bands, a multiplier, and a tolerance band. 5-band resistors offer three digits for higher precision. 6-band resistors add a temperature coefficient band. The system was developed by the Radio Manufacturers Association in the 1920s to standardize identification, replacing printed numbers that faded. Popular mnemonics help memorize the sequence, such as “Black Brown Red Orange Yellow Green Blue Violet Gray White” or the phrase “Big Brown Rabbits Often Yield Great Big Vocal Groans When Gingerly Slapped.” Tolerance bands are usually gold (±5%) or silver (±10%), while brown indicates ±1%. Surface-mount resistors use alphanumeric codes, but through-hole resistors still widely use the color band system.

Correct reading requires orientation: the tolerance band is slightly separated or has a distinct color. For example, a resistor with brown, black, red, and gold bands indicates 1.0 kΩ with 5% tolerance. The multiplier (red = ×100) sets the magnitude. Precision resistors (5 bands) use brown for 1% and red for 2% tolerance. The temperature coefficient, present on the sixth band, is expressed in ppm/°C, with colors like brown (100 ppm), red (50), and orange (15). This system is crucial for repairs and projects, enabling quick value identification without instruments.

There are also non-standard colors, like pink used in some military resistors, and special codes for power resistors. International standardization was consolidated by the IEC in the 1960s, unifying codes that previously differed between the US and Europe. Despite digital multimeters, band reading remains a fundamental skill taught in electronics courses.

Frequently Asked Questions

How to read resistor color bands?

Identify the tolerance band (usually gold or silver, separated). Read bands from left to right: the first ones are digits, the next is the multiplier. Use the color code chart to convert each color to a number.

What does a gold band on a resistor mean?

A gold band indicates a tolerance of ±5%. This means the actual resistance can vary up to 5% above or below the nominal value.

What is the difference between 4-band and 5-band resistors?

4-band resistors have two digit bands, a multiplier, and a tolerance band. 5-band resistors have three digit bands, allowing higher precision (e.g., 1% tolerance vs. 5% for most 4-band resistors).