Resistor color bands

The colored bands on resistors indicate their electrical value and tolerance, essential for electronic circuits.

About this subject

Resistors are passive components that limit current flow in electrical circuits. Their values are encoded by colored bands, an internationally standardized system per IEC 60062. Typically, a resistor has 4 to 6 bands: the first few represent significant digits, the next is the multiplier, and the last indicates tolerance (or, in 5 or 6 band versions, temperature coefficient).

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 is a power of 10, with colors like gold (×0.1) and silver (×0.01). Tolerance, in percentage, also has colors: brown (±1%), red (±2%), gold (±5%), and silver (±10%). Resistors without a tolerance band (only 3 bands) have ±20% tolerance.

To read a resistor, position the tolerance band (usually gold or silver) to the right. For example, a resistor with bands brown, black, red, gold: brown=1, black=0, red=×100, gold=±5%. This yields 10 × 100 = 1000 ohms (1 kΩ) with 5% tolerance. The color code is essential for technicians and hobbyists to identify values without meters, speeding up repairs and projects.

A curiosity: the color code originated in the 1920s, standardized by the RMA (Radio Manufacturers Association) in the US, to facilitate mass production of radios. Today, SMD resistors use numeric codes, but the band code remains common for through-hole components.

Frequently Asked Questions

How do I read a 4-band resistor?

Place the tolerance band (gold or silver) to the right. The first two bands are digits, the third is the multiplier. Example: brown, black, red, gold = 1, 0, ×100 = 1000 Ω (1 kΩ) ±5%.

What is the difference between 4, 5, and 6 band resistors?

4-band resistors have two digits, a multiplier, and tolerance. 5-band resistors have three digits for higher precision. 6-band resistors add a band for temperature coefficient, indicating how resistance changes with temperature.

What does the gold band on a resistor mean?

A gold band can be a multiplier (×0.1) or tolerance (±5%). It usually appears as the last band (tolerance) or as the third band in some precision resistors. Its position determines its meaning.