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Resistor color code Calculator

by | Last updated Sep 1, 2021 | Electrical Tools

Are you struggling to find the values of different resistors? If so, this electrical calculator might help you to read the resistor color code. Using this calculator, you can find the value of 4-band, 5-band and 6-band resistors.

So, how to use this calculator?

  • First, select the number of bands in the resistor.
  • Depending on the number of bands, select the colors of each band in respective dropdown.
  • Click the calculate button to see the resistor value.

Additionally, you can also use the series and parallel resistance calculator to find the resistance value when they are connected in series and parallel respectively. Learn more about the resistors in detail.

Resistor Bands

For 4-band resistors, the four bands include 2 significant digits (represented by different colors), a multiplier band and a tolerance band.

Five band resistors consist of 5 bands, which include 3 significant digits (represented by different colors), a multiplier band and a tolerance band.

Similarly, 6-band resistors have six bands that include 3 significant digits (represented by different colors), a multiplier band, a tolerance band and a sixth band that represents the temperature coefficient.

The following figure shows the different band colors and their equivalent digits used to find the resistor values.

Resistor color code

Significant digits

The first and second band corresponds to the significant digits in 4-band resistors. Whereas, in 5-band and 6-band resistors, the first three bands correspond to the significant digits.

It comprises of 10 colors: black, brown, red, orange, yellow, green, blue, violet, grey and white. These 10 colors represent significant digits from 0 to 9, as shown in the above figure. For example, red color corresponds to ‘2’, grey color represents to ‘8’ and so on.

The order of the colors(from black to white) can be easily remembered from the saying “BB ROY of Great Britain has a Very Good Wife”. In this, the first letter(in bold) signifies the color order BBROYGBVGW.

Multiplier

For 4-band resistors, the third band is the multiplier band. Similarly, for 5-band and 6-band resistors, the fourth band is the multiplier band.

The multiplier band of a resistor has 12 different color code: black, brown, red, orange, yellow, green, blue, violet, grey, white, gold and silver. A value is assigned for each color, which is multiplied with the significant digits in the previous bands.

If the multiplier band is Green color, 100000 should be multiplied with the digits in the previous bands.

How to find the resistor value?

For better understanding, let us consider the 4-band resistor. In this resistor, let the first band be blue color, the second band be grey color and third band(multiplier band) is red color.

Now to find the resistor value, identify the significant digits of the first and second bands(Here it is blue = 6 and Grey = 8). Also, identify the value assigned for the third band. For red color, the assigned multiplier is 100.

Finally, concatenate the digits(6, 8) and multiply it by 100 to get the resistor vaue. The value is 6800 Ω = 6.8k Ω.

Similarly, for 5-band and 6-band resistors, the resistor value can be calculated. Let the first band be yellow, the second band be violet and the third band be black color. The color of the fourth band (i.e. multiplier band ) be orange.

Once the color is known, identify the value assigned for each color. Concatenate the significant digits and multiply it with the multiplier value to get the resistor value, as shown below.

Tolerance

The last band of the 4-band and 5-band resistors indicate the tolerance band. But in 6-band resistor, the tolerance band is at the 5th band.

The tolerance band indicates that the actual value of the resistor may vary within the specified tolerance level. For example, let us consider a 100 Ω resistor and it has a tolerance value of ±10%. It means, the nominal value of the resistor is 100 Ω, but the actual measured value may range between 90 Ω to 110 Ω.

The tolerance band has 10 colors: brown, red, orange, yellow, green, blue, violet, grey, gold and silver. Each color represents a specific tolerance value. For example, the tolerance value of brown color is ±1%, for red color = ±2% and so on.

Temperature Co-efficient

Generally, 6-band resistor is a high precision resistor, in which its last band has 6 different color code. This band indicates the temperature coefficient of the resistor. It is not available in 4-band and 5-band resistors.

The temperature coefficient of resistance is one of the important characteristics of a resistor. It can be defined as the change in resistance caused due to the change in temperature. It is expressed in either ppm/0C (or) ppm/K, which stands for parts per million per degree Celcius(or Kelvin).

The temperature coefficient of a resistor(TCR) is given by a formula,

    \[TCR = \frac{R_2 - R_1}{R_1(T_2 - T_1)} . 10^{-6} \]

For example, let us assume that the color of the sixth band is brown. It corresponds to the temperature coefficient value of 100 ppm/0C. This means, for a temperature change of 1˚C, the resistance value can change to 100 ppm.

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