Resistor Color Code Calculator

Decode 3, 4, 5, and 6-band resistors to ohms, tolerance, and temperature coefficient — or convert any resistance value back to its EIA color bands.

Number of bands

How Resistor Color Codes Work

The resistor color code is an EIA-standardized system for marking axial lead resistors with colored bands that encode resistance, tolerance, and (optionally) temperature coefficient. Each color maps to a digit 0–9, a multiplier, a tolerance percentage, or a temperature coefficient value.

Reading order: bands are read from the end closest to the lead (the side with bands grouped together) toward the center of the body. The last band (usually separated by a larger gap) indicates tolerance — and on 6-band resistors, the very last band indicates the temperature coefficient.

Color Code Reference Table

Color Digit Multiplier Tolerance Temp. Coeff. (ppm/°C)

Reading a 4-Band Resistor

A 4-band resistor uses the first two bands for significant digits, the third as the multiplier (power of ten), and the fourth for tolerance. For example, Yellow-Violet-Red-Gold = 4, 7, ×100, ±5% = 4700 Ω ±5% (4.7 kΩ).

5- and 6-band resistors add a third significant digit, giving finer resolution for precision resistors. The 6th band denotes the temperature coefficient (TCR), important in precision and stability-critical circuits like oscillators and measurement bridges.

FAQ

Which side of the resistor do I read from?
Read from the side where the bands are grouped closest to the end of the body. The tolerance band is usually separated from the value bands by a slightly larger gap and is often a metallic color (gold or silver). When in doubt, the gold/silver/precision band is the tolerance and belongs on the right.
What's the difference between 3, 4, 5, and 6-band resistors?
A 3-band resistor has two significant digits + multiplier and an implied ±20% tolerance. 4-band adds an explicit tolerance band (the most common type). 5-band adds a third significant digit for precision values (typically ±1% or better). 6-band adds a temperature coefficient band for high-stability applications.
How do I write resistance values like 4.7 kΩ or 0.5 Ω as text?
Use the convention: R for ohms (4R7 = 4.7 Ω), k or K for kilohms (4k7 = 4.7 kΩ), and M for megohms (1M = 1 MΩ). The letter replaces the decimal point, which prevents misreading when decimal marks are smudged on small components.
Why is gold/silver used as a multiplier that makes the value smaller?
Gold (×0.1) and silver (×0.01) are used to encode resistances below 10 Ω, since the standard digit multipliers (×1, ×10, ×100, …) can't reach sub-10 Ω values. For example, Red-Red-Gold = 2, 2, ×0.1 = 2.2 Ω.
What does the temperature coefficient (TCR) band mean?
The TCR, in parts per million per degree Celsius (ppm/°C), describes how much the resistance drifts with temperature. Lower is better for precision circuits. For example, a brown 6th band (100 ppm/°C) means a 100 Ω resistor changes by 100 × 100 × 10⁻⁶ = 0.01 Ω per °C of temperature change.

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