Carbon resistor Color code | how to calculate?

In Physics or Electronics labs you may have seen carbon resistors. This type of resistors is usually painted with three, four, five or six bands of different colors. These bands are the codes from which we can find the value of resistance of a resistor. Now, how to read resistor color code of carbon resistors? Go through this article and then you will never ask this question to anyone.

Contents in this article:

  1. What is a Carbon resistor?
  2. How to read resistor color code?
  3. Resistor color code chart
  4. Example of resistor color code reading

What do you mean by a Carbon resistor?

Carbon resistors
Carbon resistors

Carbon resistors are cylindrical shaped small metallic resistors which are commonly used in analog electronic and electrical circuits for laboratory based works. These consist of zebra-like bands of different colors on their bodies which are the codes to find the values of resistance of the resistors.

How to read resistor color code of carbon resistors?

To calculate the resistance of a carbon resistor, we need to read its color code. A carbon resistor may have three bands, four bands or five bands on its body. Every color refers to a digit or letter. Therefore, the color code for a resistor contains numbers and letters. In this section, we have explained the rules of resistor color code for 3, 4, 5 and 6 band carbon resistor. To calculate the resistance you need to follow the following rules and the resistor color code chart at next section.

3 bands carbon resistor color code rule

For a three band carbon resistor, the color code is as followings –

  • First band gives first digit (leftmost) of the resistance value
  • Second band gives second digit (from the left) of the resistance value
  • Third band gives the multiplier i.e. the number of zeros after the second digit.

4 bands resistor color code rule

For a Four band carbon resistor, the color code is as followings –

  • First band gives first digit (leftmost) of the resistance value
  • Second band gives second digit (from the left) of the resistance value
  • Third band gives number of zeros after the second digit.
  • Fourth band gives the tolerance i.e. the percentage error that the resistance value can have.

5 bands resistor color code rule

For a Five band carbon resistor, the color code is as followings –

  • First band gives first digit (leftmost) of the resistance value
  • Second band gives second digit (from the left) of the resistance value
  • Third band gives third digit from the left.
  • Fourth band gives the multiplier i.e. number of zeros after third digit.
  • Fifth band gives the tolerance i.e. the percentage error that the resistance value can have.

6 bands resistor color code rule

For a six band carbon resistor, the color code is as followings –

  • First band gives first digit (leftmost) of the resistance value.
  • Second band gives second digit (from the left) of the resistance value.
  • Third band gives the third digit from the left of resistance value.
  • Fourth band of carbon resistor gives the multiplier i.e. number of zeros after the third digit.
  • Fifth band gives the tolerance i.e. the percentage error that the resistance value can have.
  • Sixth band gives the temperature co-efficient of the resistor.

Resistor color code chart

Now, what will be the first and second digit of the resistance? How many zeros will be there after the second digit? These are very simple. First three color-bands on carbon resistor indicate three number between 0 to 9. Similarly, some other colors represent percentage of tolerance, multiplier and temperature co-efficient. Check the resistor color code chart for the details.

ColorCorresponding digit
(Code)
MultiplierPercentage tolerance
(Code)
Temperature Coefficient
Black01
Brown1101% (F)100
Red21022% (G)50
Orange31033%15
Yellow41044%25
Green51050.5
Blue61060.25
Violet71070.1
Grey8108
White9109
Golden0.15% (J)
Silver0.0110% (K)
No Band20% (M)
Carbon resistor color code chart

The decimal symbol is coded by the alphabet “R“.

Example of resistor color code reading

1.5k ohm carbon resistor
1.5k ohm carbon resistor

Consider a 1500 ohm carbon resistor with 4 bands. Colors of the bands will be Brown, Green, Red and Golden. Then, first two digits are 1 and 5 and the multiple is 100 i.e. there are two zeros after first two digits. The fourth band of Golden color which implies that the tolerance in resistance is 5%. Then the resistor color coding of 4 bands 1.5k ohm resistance is 152J.

Band NumberColorCode
1st BandBrown1
2nd BandGreen5
3rd BandRed2
4th BandGoldenJ
Color coding of 1.5k resistor

Thus, the code 152J represents the resistance value of \small \color{Blue}1500 \Omega \pm 5%.

Check some other examples in details:

  1. 100 Ohm resistor Color code
  2. Color code for 1k ohm resistor with 3, 4, 5 and 6 bands.
  3. 10k ohm resistor Color code

Let’s practice it!

Question: Find the color code for 220 ohm and 330 ohm carbon resistors.

This is all from this article on how to calculate resistor color code of carbon resistors? Hope you have understand the procedure. I advise you to take any random resistor and try to find the resistance of that resistor by own. If you still have any doubt on this topic you can ask me in the comment section.

Thank you!

Related posts:

  1. 1k Ohm resistor color code
  2. Ohm’s Law of current and voltage
  3. Series and Parallel combination of resistors