# Resistor Color Code Calculator

Resistance is a property that describes how a material or component resists the flow of electrical current. It is the ratio of voltage (V) applied across a component to the current (I) passing through it and is expressed as R = V/I.

The color bands on a resistor are used to represent the resistance value, tolerance, and sometimes the temperature coefficient of the resistor. These color bands follow a standardized color code to help identify the resistor's characteristics. The number of color bands on a resistor can vary, but most commonly, you will find resistors with either four or five bands.

Significant Figure Bands (1st and 2nd Bands): These bands represent the significant digits of the resistance value. Each color corresponds to a specific number, typically from 0 to 9. The first band represents the tens digit, and the second band represents the units digit.

ColorValue
Black0
Brown1
Red2
Orange3
Yellow4
Green5
Blue6
Violet7
Gray8

Multiplier Band (3rd Band): This band represents the multiplier that should be applied to the significant figures to get the full resistance value. Each color corresponds to a power of 10.

ColorValue
Blackx1
Brownx10
Redx100
Orangex1,000
Yellowx10,000
Greenx100,000
Bluex1,000,000
Violetx10,000,000
Gray(rarely used for multipliers)
White(rarely used for multipliers)

Tolerance Band (4th Band, if present): The tolerance band indicates the allowable percentage deviation from the nominal resistance value. The most common tolerance values are:

ColorValue
Gold±5%
Silver±10%
No color (bare)±20%

Temperature Coefficient Band (5th Band, if present): Some resistors, especially precision resistors, include a fifth band to indicate the temperature coefficient. The temperature coefficient band tells you how much the resistor's resistance changes with temperature.

ColorValue
Brown±100 ppm/°C (parts per million per degree Celsius)
Red±50 ppm/°C
Orange±15 ppm/°C
Yellow±25 ppm/°C
Blue±10 ppm/°C

Sixth Band (Temperature Coefficient or Reliability):
The sixth band, if present, provides information about the temperature coefficient or, in some cases, the reliability or failure rate of the resistor.

ColorValue
Brown±100 ppm/°C (parts per million per degree Celsius)
Red±50 ppm/°C
Orange±15 ppm/°C
Yellow±25 ppm/°C
Blue±10 ppm/°C

Factors Affecting Resistance:

• Material: Different materials have different electrical resistivity, which influence their resistance. For example, metals like copper have low resistivity, making them good conductors, while insulators have high resistivity.
• Length: The longer a wire or component, the more resistance it typically has.
• Cross-Sectional Area: A wider cross-sectional area generally results in less resistance.
• Temperature: Resistance can change with temperature. Some materials, like conductors, generally have increasing resistance with temperature, while semiconductors may decrease in resistance with higher temperatures.