Resistor color codes are a system of marking the value, tolerance, and sometimes the temperature coefficient of a resistor using colored bands. The color code is used to identify the resistance value and other important information about a resistor. In this article we learn about Resistor Color Codes.
The Resistor Color Codes consists of several colored bands, typically four or five, that are printed on the body of the resistor. The first two or three bands represent the resistance value, while the fourth band represents the tolerance. If there is a fifth band, it represents the temperature coefficient.
The following table shows the Resistor Color Codes for resistors:
| Color | 1st Band | 2nd Band | 3rd Band | 4th Band | 5th Band |
| Black | 0 | 0 | 0 | – | – |
| Brown | 1 | 1 | 1 | 1% | 100 ppm/K |
| Red | 2 | 2 | 2 | 2% | 50 ppm/K |
| Orange | 3 | 3 | 3 | – | 15 ppm/K |
| Yellow | 4 | 4 | 4 | – | 25 ppm/K |
| Green | 5 | 5 | 5 | 0.5% | – |
| Blue | 6 | 6 | 6 | 0.25% | 10 ppm/K |
| Violet | 7 | 7 | 7 | 0.1% | 5 ppm/K |
| Gray | 8 | 8 | 8 | 0.05% | – |
| White | 9 | 9 | 9 | – | – |
| Gold | – | – | – | 5% | – |
| Silver | – | – | – | 10% | – |
| No color | – | – | – | 20% | – |
The resistor colour code is read from left to right as illustrated below:
The Standard Resistor Colour Code Chart
The Resistor Colour Code Table
| Colour | Digit | Multiplier | Tolerance |
| Black | 0 | 1 | |
| Brown | 1 | 10 | ± 1% |
| Red | 2 | 100 | ± 2% |
| Orange | 3 | 1,000 | |
| Yellow | 4 | 10,000 | |
| Green | 5 | 100,000 | ± 0.5% |
| Blue | 6 | 1,000,000 | ± 0.25% |
| Violet | 7 | 10,000,000 | ± 0.1% |
| Grey | 8 | ± 0.05% | |
| White | 9 | ||
| Gold | 0.1 | ± 5% | |
| Silver | 0.01 | ± 10% | |
| None | ± 20% |
Then we can summerise the different weighted positions of each coloured band which makes up the resistors colour code above in the following table:
| Number of Coloured Bands |
3 Coloured Bands (E6 Series) |
4 Coloured Bands (E12 Series) |
5 Coloured Bands (E48 Series) |
6 Coloured Bands (E96 Series) |
| 1st Band | 1st Digit | 1st Digit | 1st Digit | 1st Digit |
| 2nd Band | 2nd Digit | 2nd Digit | 2nd Digit | 2nd Digit |
| 3rd Band | Multiplier | Multiplier | 3rd Digit | 3rd Digit |
| 4th Band | – | Tolerance | Multiplier | Multiplier |
| 5th Band | – | – | Tolerance | Tolerance |
| 6th Band | – | – | – | Temperature Coefficient |
Calculating Resistor Colour Code Values
To calculate the value of a resistor using the color code, you need to identify the color of each band and their corresponding values.
The color code for a standard four-band resistor is as follows:
- The first band represents the first digit of the resistance value.
- The second band represents the second digit of the resistance value.
- The third band represents the multiplier for the resistance value.
- The fourth band represents the tolerance value.
Here are the steps to follow to calculate the value of a four-band resistor:
- Identify the color of the first band and match it to the corresponding number from the above table.
- Identify the color of the second band and match it to the corresponding number from the above table.
- Identify the color of the third band and match it to the corresponding multiplier from the above table. For example, if the third band is red, the multiplier is 100 ohms (10^2).
- Multiply the two-digit number formed by the first and second bands by the multiplier value from the third band. This gives you the resistance value in ohms.
- Identify the color of the fourth band and match it to the corresponding tolerance from the above table. For example, if the fourth band is gold, the tolerance is 5%.
- Calculate the tolerance range by multiplying the resistance value by the tolerance percentage. For example, if the resistance value is 1,000 ohms (1 kΩ) and the tolerance is 5%, the tolerance range is 50 ohms.
- Express the resistance value with its unit (ohms, kilohms, megohms) and tolerance range (if required).
Here’s an example:
Suppose you have a resistor with the color bands brown, black, red, and gold.
- Brown corresponds to 1.
- Black corresponds to 0.
- Red corresponds to 100 (10^2).
- Gold corresponds to ±5%.
Therefore, the resistor’s resistance value is (10 × 1) × 100 = 1,000 ohms (1 kΩ), and the tolerance range is ±5% of the resistance value, which is ±50 ohms. So the final value of the resistor would be expressed as 1 kΩ ± 50 Ω.
Tolerance Letter Coding for Resistors
In addition to the color code, some resistors are also marked with a letter code that indicates the tolerance of the resistor. This code is used in place of the fourth band of the color code on some resistors.
Here is the letter code for resistor tolerances:
| Letter code | Tolerance |
| F | ±1% |
| G | ±2% |
| J | ±5% |
| K | ±10% |
| M | ±20% |
| Z | Special |
For example, if you see a resistor with the code “4.7KJ”, it indicates that the resistance value is 4.7 kilohms with a tolerance of ±5%. The “K” indicates that the third band is orange (multiplier of 1,000), and the “J” indicates a tolerance of ±5%.
Note that the letter code is not used on all resistors, and it is more commonly used on smaller, surface-mount resistors rather than larger through-hole resistors. If a resistor has both a letter code and a fourth band, the letter code takes precedence over the fourth band for indicating the tolerance.
Surface Mount Resistors
Surface mount resistors (SMD resistors) are a type of electronic component that are designed to be mounted directly on the surface of a printed circuit board (PCB) without the need for leads or wires. They are typically smaller in size and have a lower profile than through-hole resistors, making them well-suited for high-density electronic circuits.
SMD resistors come in a variety of package sizes, each with its own code to indicate its dimensions. Some of the most common SMD resistor packages include 0402, 0603, 0805, and 1206, with the numbers indicating the length and width of the package in thousandths of an inch. For example, an 0402 package is 0.04 inches long and 0.02 inches wide.
SMD resistors also use a different coding system than through-hole resistors to indicate their resistance value and tolerance. The coding system typically consists of three or four digits, with the first two digits indicating the significant figures of the resistance value and the third digit (or fourth digit, if present) indicating the number of zeros to add to the end of the value to determine the multiplier. For example, a resistor marked “103” has a value of 10 x 10^3 ohms, or 10 kilohms.
SMD resistors may also include a letter code to indicate their tolerance, similar to through-hole resistors. Common letter codes for SMD resistors include F (±1%), G (±2%), J (±5%), and K (±10%).
In addition to their small size and low profile, SMD resistors offer other advantages over through-hole resistors, such as lower inductance and capacitance, and better high-frequency performance. However, they can be more difficult to work with due to their small size and lack of leads, and may require specialized equipment for placement and soldering.
Also read:- Summing amplifier, Norton theorem, High pass filter.
